Parse less and scss files

This pull request is for [Simple support for LESS/SCSS](https://trello.com/c/KoK6kPtp/1190-m-simple-support-for-less-scss-in-key-brackets-features).


Do we need this? Seems like we should have a well defined context of when this is attached to an editor and not have to worry about if it's being detached when there isn't an editor already attached.