Lots of small UI changes and bug fixes

Home: A modal now says it's a preview of BookOut; search when not logged
in is now functional
Join: Now mentions how to get a Google Acct
Main Template: Sign Up is now Join (to match everything else)
404 Error: New title = 404 - Page not found
505 Error: New title, minor change in wording
About BookOut: Fixed broken link
Mobile App: Rewrote
Profile: Lowered heading for books
Views: Updated search to work when not logged in