Login UI completely revamped.  Works with 4/4s/5/5s/6/6+

Launch image and login screen look good and work properly with all
relevant iPhone models.
Added auto layout constraints for login UI elements.  Screen scrolls to
accommodate keyboard (necessary for 4/4s).
Basic animation on login.
Need to fix white flash screen (order of views being presented is bad).
Need to fix register screen UI.
Other UI elements need to be added to login so that it isn’t as empty.