Small Xcode 5 related updates.
Make sure we're building against 10.8.
Remove a stray userWithBlock.
Remove usernameLabel.

Also contains tweaks to the XIBs provided by Xcode 5 (still keeping
Xcode 4.6 compatability).
Remove UserNameTextField (the class).
(Temporarily) remove the mouseDown on UserImageView.
Change the class prefix. Assign our team to the project.
Add a no-op showAbout. Add showProfile and a new menu item.
Add AboutWindowController.
Fixing a few bugs regarding AboutWindowController.