Failed test can't be re runned if the failed test use Codeception/Specify

#### What are you trying to achieve?

Re run the failed tests:

```
./codecept run -g failed
```
#### What do you get instead?

Failed tests that use `Codeception/Specify` won't run. This problem only affects these tests.
#### How to reproduce

Create test file:

``` php
class FailedTest extends \Codeception\Test\Unit
{
use \Codeception\Specify;

public function testWithSpecify()
{
$this->specify('Specification', function () {
$this->assertFalse(true, 'Message 1');
});
}

public function testWithoutSpecify()
{
$this->assertFalse(true, 'Message 2');
}
}
```

Run tests:

```
$ ./codecept run
Codeception PHP Testing Framework v2.2.3
Powered by PHPUnit 5.4.8 by Sebastian Bergmann and contributors.

Acceptance Tests (0) --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Functional Tests (0) --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Unit Tests (2) --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
✖ FailedTest: With specify | specification | examples index 0
✔ FailedTest: With specify (0.01s)
✖ FailedTest: Without specify (0.00s)
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Time: 167 ms, Memory: 8.00MB

There were 2 failures:

---------
1) FailedTest: With specify | specification | examples index 0
Test tests/unit/FailedTest.php:testWithSpecify | Specification | examples index 0
Message 1
Failed asserting that true is false.
Codeception/Codeception#1 /mnt/store-ssd/work/codeception/tests/unit/FailedTest.php:11
Codeception/Codeception#2 FailedTest->{closure}
Codeception/Codeception#3 /mnt/store-ssd/work/codeception/tests/unit/FailedTest.php:12
Codeception/Codeception#4 FailedTest->testWithSpecify

---------
2) FailedTest: Without specify
Test tests/unit/FailedTest.php:testWithoutSpecify
Message 2
Failed asserting that true is false.
Codeception/Codeception#1 /mnt/store-ssd/work/codeception/tests/unit/FailedTest.php:17
Codeception/Codeception#2 FailedTest->testWithoutSpecify

FAILURES!
Tests: 2, Assertions: 2, Failures: 2.
```

`_output/failed` now contains the tests:

```
tests/unit/FailedTest.php:testWithSpecify | Specification | examples index 0
tests/unit/FailedTest.php:testWithoutSpecify
```

Run failed tests:

```
$ ./codecept run -g failed
Codeception PHP Testing Framework v2.2.3
Powered by PHPUnit 5.4.8 by Sebastian Bergmann and contributors.
[Groups] failed

Acceptance Tests (0) --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Functional Tests (0) --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Unit Tests (1) --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
✖ FailedTest: Without specify (0.01s)
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Time: 195 ms, Memory: 8.00MB

There was 1 failure:

---------
1) FailedTest: Without specify
Test tests/unit/FailedTest.php:testWithoutSpecify
Message 2
Failed asserting that true is false.
Codeception/Codeception#1 /mnt/store-ssd/work/codeception/tests/unit/FailedTest.php:17
Codeception/Codeception#2 FailedTest->testWithoutSpecify

FAILURES!
Tests: 1, Assertions: 1, Failures: 1.
```

**Note**: Only `testWithoutSpecify` runned.
#### Possible solution

I did some digging, and maybe I found the problem. I think that in [Lib\GroupManager](https://github.com/Codeception/Codeception/blob/2.2/src/Codeception/Lib/GroupManager.php#L121) an `strpos()` call's parameters are swapped.

The `$testPattern` contains: `/mnt/store-ssd/work/codeception/tests/unit/FailedTest.php:testWithSpecify | Specification | examples index 0`.
And `$filename . ':' . $test->getName(false)` is: `/mnt/store-ssd/work/codeception/tests/unit/FailedTest.php:testWithSpecify`.

So the `strpos()` returns `false`. But if I swap the two parameters, the all the failed tests are re runned.

I am new to Codeception, so I might be wrong (I haven't set up the tests, so I can't verify that this change doesn't break anything).
### Details
- Codeception version: 2.2.3
- PHP Version: 7.0.8
- Operating System: Ubuntu 16.04.1 LTS
- Installation type: Composer
- List of installed packages (`composer show`)

```
behat/gherkin v4.4.1 Gherkin DSL parser for PHP 5.3
codeception/codeception 2.2.3 BDD-style testing framework
codeception/specify 0.4.3 BDD code blocks for PHPUnit and Codeception
doctrine/instantiator 1.0.5 A small, lightweight utility to instantiate objects in PHP without invoking their constructors
facebook/webdriver 1.1.2 A PHP client for WebDriver
guzzlehttp/guzzle 6.2.1 Guzzle is a PHP HTTP client library
guzzlehttp/promises 1.2.0 Guzzle promises library
guzzlehttp/psr7 1.3.1 PSR-7 message implementation
myclabs/deep-copy 1.5.1 Create deep copies (clones) of your objects
phpdocumentor/reflection-common 1.0 Common reflection classes used by phpdocumentor to reflect the code structure
phpdocumentor/reflection-docblock 3.1.0 With this component, a library can provide support for annotations via DocBlocks or otherwise retrieve information that is embedded in a DocBlock.
phpdocumentor/type-resolver 0.2
phpspec/prophecy v1.6.1 Highly opinionated mocking framework for PHP 5.3+
phpunit/php-code-coverage 4.0.1 Library that provides collection, processing, and rendering functionality for PHP code coverage information.
phpunit/php-file-iterator 1.4.1 FilterIterator implementation that filters files based on a list of suffixes.
phpunit/php-text-template 1.2.1 Simple template engine.
phpunit/php-timer 1.0.8 Utility class for timing
phpunit/php-token-stream 1.4.8 Wrapper around PHP's tokenizer extension.
phpunit/phpunit 5.4.8 The PHP Unit Testing framework.
phpunit/phpunit-mock-objects 3.2.3 Mock Object library for PHPUnit
psr/http-message 1.0 Common interface for HTTP messages
sebastian/code-unit-reverse-lookup 1.0.0 Looks up which function or method a line of code belongs to
sebastian/comparator 1.2.0 Provides the functionality to compare PHP values for equality
sebastian/diff 1.4.1 Diff implementation
sebastian/environment 1.3.7 Provides functionality to handle HHVM/PHP environments
sebastian/exporter 1.2.2 Provides the functionality to export PHP variables for visualization
sebastian/global-state 1.1.1 Snapshotting of global state
sebastian/object-enumerator 1.0.0 Traverses array structures and object graphs to enumerate all referenced objects
sebastian/recursion-context 1.0.2 Provides functionality to recursively process PHP variables
sebastian/resource-operations 1.0.0 Provides a list of PHP built-in functions that operate on resources
sebastian/version 2.0.0 Library that helps with managing the version number of Git-hosted PHP projects
symfony/browser-kit v3.1.3 Symfony BrowserKit Component
symfony/console v3.1.3 Symfony Console Component
symfony/css-selector v3.1.3 Symfony CssSelector Component
symfony/dom-crawler v3.1.3 Symfony DomCrawler Component
symfony/event-dispatcher v3.1.3 Symfony EventDispatcher Component
symfony/finder v3.1.3 Symfony Finder Component
symfony/polyfill-mbstring v1.2.0 Symfony polyfill for the Mbstring extension
symfony/yaml v3.1.3 Symfony Yaml Component
webmozart/assert 1.0.2 Assertions to validate method input/output with nice error messages.
```
- Suite configuration:

I have set up a new project to demonstrate this. I've installed Codeception and Specify with composer (`composer require codeception/codeception codeception/specify`), and I've run bootstrap: `./codecept bootstrap`.

So, there is nothing special, default installation:

``` yml
actor: Tester
paths:
tests: tests
log: tests/_output
data: tests/_data
support: tests/_support
envs: tests/_envs
settings:
bootstrap: _bootstrap.php
colors: true
memory_limit: 1024M
extensions:
enabled:
- Codeception\Extension\RunFailed
modules:
config:
Db:
dsn: ''
user: ''
password: ''
dump: tests/_data/dump.sql
```

``` yml
# Codeception Test Suite Configuration
#
# Suite for unit (internal) tests.

class_name: UnitTester
modules:
enabled:
- Asserts
- \Helper\Unit
```

Bắt đầu trong Lib\GroupManager.php tại lệnh gọi strpos() được issue đề cập, sau đó tái hiện lỗi bằng ./codecept run -g failed với một test có chứa Codeception\Specify. Hoàn tất khi nhóm failed-test chạy lại cả các lỗi Specify và non-Specify được liệt kê trong _output/failed.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.