Use the correct syntax to reference a github repository.

The previous syntax was creating an error in my project using
grunt-bower-task.

grunt-bower copying
Fatal error: ENOENT, no such file or directory 'vendor/antiscroll'
Fix jquery-mousewheel dependency
Fix build error due to ember-template-compiler

ember-template-compiler released version 1.9 with breaking changes, which
grunt-ember-templates pulls in by default. Lock the version number at 1.7
for now (hopefully grunt-ember-templates will do the same).
Fix usebanner and default grunt build

Previously, the dist files banner would be lost when running grunt watch
(because usebanner wouldn't be called). This makes sure it's called after
changes to dist files.

It also fixes other small problems in the default grunt build - adds clean
to the start of the grunt task, and adds uglify in some places to make sure
the min js file actually gets updated. Should fix a few build frustrations.