Mms: Add native heads up support

Add heads up support (optional but enabled by default).

Shows important messages of this app as heads up.

Means:
- All MMS
- SMS if quickpopup is disabled

Other messages like storage or blacklist notifications are not important and will not show as heads up

PS:
- show always as expanded.....so user can directly interact with it

Change-Id: Id83633610c18ab4e380bfb910ea50e8bf7b61be6

Conflicts:
	res/values/slim_strings.xml
	res/xml/preferences.xml
	src/com/android/mms/ui/MessagingPreferenceActivity.java

Conflicts:
	res/values/cm_strings.xml
	src/com/android/mms/ui/MessagingPreferenceActivity.java
fix build
mms: do not update seen field in markAsUnread operation

This prevents to a seen thread to be notified again after mark as unread

Change-Id: Ib97ded493cdddb261666cffb37bf2f82e827d6a3
Signed-off-by: Jorge Ruesga <jorge@ruesga.com>
mms: markAsUnread only read items (ignore seen flag)

Do not mark threads that are only seen

Change-Id: Iffef7823663918ee0dcbecc0241cde71e5a25bca
Signed-off-by: Jorge Ruesga <jorge@ruesga.com>
mms: markAllAsUnread is never called

The actual markAllAsUnread code is never called. It requires a new menu to be launched.

Change-Id: If620ca3c41aa091e065ff7646091bc118a072e5d