fakedb for mocking SQL databases

This could be a layer on top of mocking just for certain PDO objects or a separate daemon if needed.

``` php
public function testFetchingAPerson()
{
$this->fakedb->stub(
'SELECT * FROM people WHERE id = 123',
['id' => 123, 'name' => 'John Smith']
);
$fetcher = new Person();
$this->assert($fetcher->get(123))->equals(['id' => 123, 'name' => 'John Smith']);
}

public function testAddingAPerson()
{
$this->fakedb->expectInsert('people', ['name' => 'John Smith']);
$person = new Person();
$person->name = 'John Smith';
$person->save();
}
```