Extract the check for case-insensitive-usernames into its own method in the User model. Also - add a test to check that it works.

Not completely sure that the test would be how you would do it... but it's passing!

Also - called `git fetch upstream master` -- and it doesn't change my code at all, so I assume it's good! :D

Let me know if I need to do anything and re-submit this.

Thanks!