Adding in CUSTOM_NOTIFICATION to contacts so that notification sounds can be assigned on a per contact basis rather than system wide.

Change-Id: I850eb7833adcf3f57fc363ea502381f8ceecc126

Conflicts:
	src/com/android/providers/contacts/ContactsDatabaseHelper.java
	src/com/android/providers/contacts/ContactsProvider2.java
	src/com/android/providers/contacts/aggregation/ContactAggregator.java