improving acceptance test matchers semantics

With the addition of #5259 we introduced several new matchers to the acceptance test framework, some of them could be improved semantical speaking, see https://github.com/elastic/logstash/pull/5259#discussion_r63837433 for details on former discussions.

This basically means we prefer something like:

```
expect(logstash).to have_installed?("logstash-input-foo").with_version("0.1.1")
```

instead of

```
expect(logstash).to have_installed?("logstash-input-foo", "0.1.1")
```

as is easier to read and deal with.