Added documentation link to login page, amde login page accessible after login by clicking the SMILE logo, hid correct answer choices from moderators during sessions, and fixed two bugs: 1) correct answers were not showing up at the right times for Public and Group questions, and 2) duplicate notification messages were appearing during Sessions when the organizer changed the sesession mode.
Merge branch 'master' of github.com:SMILEConsortium/smile_global