Avoid IllegalArgumentException in Preference.java compareTo()

In some situations the collection.sort() algoritm fails in compareTo()
with a: java.lang.IllegalArgumentException: Comparison method violates
its general contract!, due to a more strict validation of the compare
contract.
This strict validation was introduced in java 1.7.
See http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6804124
This fix should prevent the sorting from crashing.

Change-Id: I64230e7f62f83c99d7a6274964bb2988ae843826
Fix CalendarView to show the month title properly.

Step to reproduce:
Do this test on a Tablet (i.e. do in multi-pane layout)
1. Settings > Date & time > Uncheck the Automatic date & time checkbox.
2. Select 'Set date' and set the month to January and Done.
3. Re-select 'Set date' then you will find no month title just above the calendar.

Change-Id: I2489b454a4526be13f1fbdc61a72edcd6b6942a0