Per conversation notification settings/ringtones

Added per conversation options. Right now the only options for each
conversation is custom notification ringtone, vibration settings.

This is useful as for each thread, you can have a custom ringtone.

The implementation is done with a custom database. This is ideal as we
don't want to modify sqlite database from google as if they upgrade, we
will run into a lot of trouble.

Github branch:
https://github.com/shuhaowu/android_packages_apps_Mms/tree/per-thread-options

PS4: Minor changes from comments.

Change-Id: I8e8e533cdcda14b3bc6adea0bb0db04cfbf0ce2b