Big update

-Removed the idea of a dataitem, now there are no interfaces, just a
list of announcements and graded work in course, and graded work is
inherited by assignments and tests.  since announcements will no longer
be in the list of upcoming, they have been moved to a "announcements"
tab
-Removed the add tab, since (like gmail) we should be able to have a
well designed UI button in the top bar
-The add tab is now Announcements
-we need better tab names
-the new add activity will have a dynamic dropdown for smart templates
for assignments
-along with the add button, we'll need the sync with google calendar
button in the top bar too