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).


It seems very special-casey that we require an exact match for non-`{` opening brackets and all closing brackets, for for `{` opening brackets we also accept other tokens as long as they _end_ in the desired char.  Would it be better to just generalize this test like `if(token.indexOf(startChar) !== -1)`?  If not, we should add a comment at the top calling out the special-case behavior more explicitly.