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).


This will "invert" the `bracketsPair` objects on every call to this function, right? I think it's too expensive, especially since the result is the same very time. This should only be done once:

```JS
    var bracketPairs = { "{": "}",
                         "[": "]",
                         "(": ")" },
        bracketPairsInverted = _.invert(bracketPairs);
```