support es6 in external js files

[rosshadden]

This will be easy now that we moved to 6to5.

We'll just transpile things in private/js/ to public/js/.

It should be togglable in the config.

[optikalefx]

it should say compiler: {}. someone might want...... COFFEESCRIPT.

[rosshadden]

Yeah..... guess we have to handle those kinds of people. And typescript, etc. Obviously(?) these would be cs-* modules. Even 6to5 could/should be it's own module I suppose.

[optikalefx]

Maybe, we should just look at what we have to do to compile the private folder. I suppose they would be cs-* modules. it should compile into the same dir structure in public for easy debugging. And then a later grunt file could expect and concat / minify that code. Even if it's coffeescript it should do the same thing. So maybe all we have to do is pass a compile function and handle the rest? If that's the case, then we don't need a cs-* we just need to know what the compile function is and use it.