added JS target (so we no longer need to call emcc by hand)
removed trailing whitespaces
moved to better error interface with a string reference for errors
do not use hardcoded g++ neither em++
Merge remote-tracking branch 'rod/emscripten' into emscripten

Conflicts:
	js/console.html
	js/libsass.worker.js
	js/worker.html
Merge pull request #3 from ckruse/emscripten

fixing error message retrieval by using the char ** pointer. making proper use of Makefile magic.