chore(grunt): switch to the new //# sourceMappingURL pragma

All browsers except from Chrome implemented both the old
"//@ sourceMappingURL" and the new "//# sourceMappingURL" pragmas
in the same version so the only reason to keep the old one was Chrome.
However, Chrome 29, i.e. current stable version already supports
the new pragma so there's no need to wait any longer.
Merge branch 'master' of https://github.com/angular/angular.js
componentizd!