LESS Compiler

[JosefJezek]

Could you add support for LESS Compiler?

https://gist.github.com/11250292

[bfintal]

Also found this less compiler to add to the list https://github.com/leafo/lessphp

I dunno though about this one, need comments of others here as well whether it would be good to add both LESS and SASS for compiling the css parameter.

Lastly, if we implement this, would this be a good handling logic?

1. Try compiling using SASS,
2. If it fails, try compiling using LESS,
3. If it fails, then just use it as is.