Messaging: Add the ability to mark a message as read from the notification

Note: It will only shows on single threads, just like the Call action

Also tweaks the settings strings a bit

Change-Id: Ie584b8f6b9d8a02005d55bfa99479c5bf5b87e56

Conflicts:

	AndroidManifest.xml
	res/values/strings.xml
	src/com/android/mms/quickmessage/QmMarkRead.java
	src/com/android/mms/transaction/MessagingNotification.java