Fix bug #1661857 (switch from using meta feed to the new allcalendars feed)

- add support for new database schema for Calendars table (new columns: selfUrl, editUrl, alternateUrl, eventsUrl)
- add database upgrade code
- update Events.DELETE constant
- add Calendars Entity support

Change-Id: I040d153ce9ba15f77b582c083a79ea6e8e777535
b/2550724 Clean up of https://android-git.corp.google.com/g/#change,46783

No functional change. Just clean up per code review:
Rename TextAppearance.widget_xxx to TextAppearance.XxxWidget
Added android:visibility="gone" for items that won't be visible
Replaced hard coded strings with constants in where clause e.g. "startDay" -> Instances.START_DAY
Removed EventInfo.hashCode() and EventInfo.equal(). Will be comparing .toString in the tests instead
Renamed getAppWidgetModel to buildAppWidgetModel

Change-Id: Id70b891df2323ae0af9500c3cfabc60940366934
Merge commit '7fcb12833c80a7f33a156d6ab25121bc05fc70de' into oxygen_1006

* commit '7fcb12833c80a7f33a156d6ab25121bc05fc70de':
  b/2550724 Clean up of https://android-git.corp.google.com/g/#change,46783
Merge commit '43b3eba05ef67bdd4b0a2b285b6ed2b377c136c5' into oxygen_1006

* commit '43b3eba05ef67bdd4b0a2b285b6ed2b377c136c5':
  Fix bug #1661857 (switch from using meta feed to the new allcalendars feed)

Conflicts:
	src/com/android/providers/calendar/CalendarDatabaseHelper.java
	src/com/android/providers/calendar/CalendarProvider2.java