Add ability to send options to compilers

[Munter]

No description provided.

[Munter]

Idea from the discussion after JSUnconf:

Let people configure the individual compiler engines with a dotfile per engine. So for sass it would be .scssrc, babel .babelrc etc. Depending on how big a combined configuration file might become this would be an option

[Munter]

Babel already decided to go this way, which I think validates the idea: https://babeljs.io/docs/usage/babelrc/

The optional package.json entry is a nice touch as well if devs don't like to concept of to many files.