Added logout button
When the user is logged in and the new logout button is shown, the user name and password fields and login button are hidden. Upon tapping the logout button these hidden elements are revealed with animation.
Login keyboard Done button submits login credentials

Also tap on login page or login button when username but no password shifts focus to password. Tap when no username shifts focus to username. Tap when neither shifts focus to username. Double tap hides keyboard.
Added recover password button to login page
Merge pull request #76 from montehurd/logoutButton

Added logout button