Added addComment API request with its tests and minor fixes
Improved user reference on comments and refactorized code about deals and its shop reference
Merge branch 'develop' into comments-and-ratings
Added more validations for comments and ratings management
Added populate for user reference into "comments.author"
Added frontend logic of comments and improved server side for properly work
Fixed requirement of one comment per user
Errors on adding comments fixed
Improved callbacks for addComent server method and added shop rating
Fixed callback of update of the deal and the shop; fixed unit tests using passportStub module

The passportStub was wrong and it has been reimplemented for project convenience.
Merge remote-tracking branch 'origin/develop' into comments-and-ratings

Conflicts:
	assets/stylesheets/gertu.styl
	assets/translations.coffee
	coverage.html
	server/controllers/deals.coffee
	server/models/deal.coffee
	server/models/shop.coffee
	test/deal/api.coffee
Improved server's responses in callbacks and added more suitable error messages in frontend for better user experience
Merge branch 'comments-and-ratings' into develop
Fixed troubles with rating and averages negative numbers
Deleted coverage.html on working tree