End of week 7 commits

Includes the following:
1. Moving Video rating formatting from the model to a decorator
2. Writing a sign up service object and corresponding test for the service object and moving relevant tests out of the users controller into the service object tests.
Also in user_controller_spec.rb:

Changed:
UserSignup.any_instance.should_receive(:sign_up).and_return(result) 
------------------->
expect_any_instance_of(UserSignup).to receive(:sign_up).and_return(result)

I presume the old one is deprecated too ?