Initial version of gutter error messages using the new Textmate API

This change adds warning images to the gutter on each line where a hinter error is found. Gutter images were introduced in `v2.0-beta.3`, so make sure your updated to that version, and you have the command line tools installed!

![screenshot 2014-10-25 02 13 06](https://cloud.githubusercontent.com/assets/710358/4778047/bf6a446a-5bdb-11e4-91b8-947ddf9ea8a8.png)

As you can see, gutter images are work in progress in Textmate, but I'll update the plugin if the API changes.