Added return before redirects

As recommended by the Cookbook:
http://book.cakephp.org/2.0/en/development/testing.html#testing-controllers

> When testing actions that contain redirect() and other code following the redirect it is generally a good idea to return when redirecting. The reason for this, is that redirect() is mocked in testing, and does not exit like normal. And instead of your code exiting, it will continue to run code following the redirect.