Ruby fixes and features

* fixed greedy strings
* added support for syntax highlighting within string interpolation
* added support for __END__ keyword

#### OLD

![screen shot 2013-08-24 at 12 46 25 pm](https://f.cloud.github.com/assets/58729/1021077/a8b5f370-0cdd-11e3-8983-cddf82a38b88.png)

#### NEW

![screen shot 2013-08-24 at 12 47 38 pm](https://f.cloud.github.com/assets/58729/1021083/048abdfc-0cde-11e3-994b-ab99c8072fcf.png)