fixed APP_REST_ROOT ref
clean up root app folder
introduced App class for util functions, including setting session data,
etc
clean up of unnecessary functions - and this file may be going away
soon.  All logic shifting to util_app.php for now
introduced helper functions for rendering login page with error message,
and checking $_SESSION for result messages to show
cleaned up logic for better naming and using helper methods
fixed logic to check for fb_userid in $_POST before getting it
lot of refactor here including clean up of generate user name , and
using helper to create a session
more cleanup and organization for user register logic - both facebook
and native
shifted UserFacebookLogic to be in logic_user.php as a 2nd class there