Added headers and user spinner to navigation drawer.
Merge remote-tracking branch 'origin/edodevelop'
Merge remote-tracking branch 'origin/paoloDevelop'
Merge remote-tracking branch 'origin/master' into edodevelop
+Added new Login Manager with corresponding interface [it now makes use
of most updated login methods for PlayServices]
+Updated UI for calendar
+Fixed issue about login and calendar listing concurrency
+Minor UI improvements