Various Minor Cleanups

Had a request to get this bundle added to the list of bundles installable in TextMate 2. Went through and reviewed the bundle and came up with a few minor cleanups.

We require the bundle to 'be' the root level of the repository, this allow makes checkout easier for those that want to contribute.

Beyond that I made a few minor scoping changes/additions to the grammar. One area I'm not sure works that well is the keyword scopes, `ONBUILD` should likely have a different scope so it stands out from the other keywords.

Thanks for your work on the bundle!