Label fix: Register to Join, Sign in to Sign In, Sign out to Log Out

Edit: Crap, I was trying to pull request the login branch. Doh!

Information Architects try to use the words people say out loud. So I hear people saying "Did you join Facebook?" or "How do I JOIN Facebook?" So I used the word Join instead of Register. It just takes a split second off the thinking time a person spends before they click on the link... making the design feel better. Feeling good and helping people accomplish their goals is what info architecture's all about!