(snippet pattern)

The Ruby snippet text generated by Cucumber causes Ruby warnings. 

![](https://dl.dropbox.com/s/7zgsfnienm3rogc/warnings.png?dl=1)

This pull request fixes that by wrapping the snippet pattern in parentheses.

To see the warning, run any file with Cucumber-generated snippet text (i.e. `foo.feature`) with `ruby -cv foo.feature`.

Adding parentheses around the text generated by `RbModule#snippet_pattern` prevents these warnings from appearing. I've updated the specs to reflect this change. I've also created an [issue](https://github.com/cucumber/cucumber/issues/328) which has more details and screenshots, as well as several comments. 

Thanks, and i'm open to feedback!

Martin