-pull
Merge branch 'master' of https://github.com/zhihaoli/QuizmTeach
Quizm Teach 2.6 [QGTab Restructuring--MAJOR STORYBOARD UPDATE]

-restructured the flow of Quiz Table View/ Group Table View
-added a QGTabVC which serves as a Tab Bar Controller for two master
tabs: Quiz Table VC and Group VC
-All user/group/question retrieval now happens in QGTabVC instead of
Quiz Table VC
-Known issue: Retrieve questions from parse is still active in Quiz
Table VC due to retrieval race condition [will leave it temporarily]
-restructured the tab views for quiz tab bar
-all quiz tab bar views have their own navigation controllers and
custom buttons
-added upload map button [not functioning]
-repositioned the export button
-ui tweaks and bug fixes