Build simplify

@b-laporte @mlaval I had 1h of downtime so took a stab at testing thing. My vision of the things is:
- run compiler tests (node-based) on each build of the framework
- runt runtime tests (browser-based) through a runner (my dream: karma + soucelabs)

Those 2 commits are going in this direction by moving all the tasks to grunt, which now is the one and only entry point to the whole build. Also, those commits are removing hand-written tasks for code that exists in npm (mostly grunt tasks).