Added Source Maps

can maybe use gulp-uglifyjs to uglify & sourcemaps but still need to
test that.
Merge branch 'master' of https://github.com/sargentsurg/Gulp-Ember-App-Kit

* 'master' of https://github.com/sargentsurg/Gulp-Ember-App-Kit:
  Update gulpfile.js

Conflicts:
	gulpfile.js