JSHint files under aura_components and extensions.
Refactor templates to pass JSHint.

Underscore dependency at extensions were removed,
I think the one at components should be good enough as an example.
Basic optimization with requirejs.

Apparently requirejs may automatically copy
files between app and dist. So I remove `copy' from build task.
May need some review on this.
Fix link to MIT license.
Merge pull request #18 from fudanchii/optimize

Some Gruntfile fixes