Update .gitignore for .idea/
Added partially working functionality to add "preferred" and "unavailable"
slots to calendar from app.
Merge branch 'master' of https://github.com/shamak/HTN_Scheduler

Conflicts:
	app/src/main/java/com/ece/htn/htn_scheduler/CalendarActivity.java
	app/src/main/java/google_calendar_api/GoogleCalendarApi.java