Treat Guardfile* as Ruby code

[mcandre]

language-ruby does a good job loading Guardfiles as Ruby code. In large projects, I like to name these Guardfile-test, Guardfile-lint, Guardfile-doc, etc. Could we please treat Guardfile* as Ruby code, so these files are colorized as well?

[kevinsawicki]

Currently glob patterns aren't supported, see atom/first-mate#25 for more details

[envygeeks]

Even just Guardfile at it's basic would be great.

[mnquintana]

@envygeeks Are you not getting syntax highlighting for Guardfiles? It is in the list of recognized filenames.

[envygeeks]

I wasn't for a while even with that line but it works now so don't worry about me!

[winstliu]

The new issue that this is blocked on is now atom/first-mate#64.