Mms: Support Folder mode and DSDS related functions

Feature requirement:
-Support inbox, sent messages, outbox, drafts and SIM card message
in folder mode; folder mode and conversation mode can be switched
alternatively.

-Add scale gesture listener to implement zoom in/out function in
folder mode.

Change-Id: I5f5622ea7c87d6c119f38dae2a0e2a52211404d0

Conflicts:
	src/com/android/mms/ui/ConversationList.java