added contacts activity and modified some activity styles
adding changes to calendar activity

- added active android support to save events and days
- using a different third party library called caldroid - it is written
on top of a gridview, easy to customize based on our needs.
Merge branch 'calendar_activity' of https://github.com/lindayang/GroupVite into calendar_activity

Conflicts:
	AndroidManifest.xml
	res/layout/activity_calendar.xml
	src/com/groupvite/CalendarActivity.java