Goes to classroom after successful attendance repoting
Merge branch 'develop' of https://bitbucket.org/yossi_gil/t6 into develop
Merge branch 'develop' of https://bitbucket.org/yossi_gil/t6 into develop
handle error on attendance screen
Merge branch 'develop' of https://bitbucket.org/yossi_gil/t6 into develop
display meaningful message on attendance error
Merge branch 'develop' of https://bitbucket.org/yossi_gil/t6 into develop

Conflicts:
	classup-client/src/il/ac/technion/cs/ssdl/cs234311/classup/gui/attendance/Attendance.java
Push notification about a new classroom event. Notification holds:
GcmKey CLASSROOM_EVENT_ID_KEY
GcmOp.NEW_CLASSROOM_EVENT

Also added getClassroomEvent to events endpoint. Haven't generated client libs for this method.
Finish push-notification-for-new-events
Cookies and session closed handling
Merge branch 'develop' of https://bitbucket.org/yossi_gil/t6 into develop