Fixes for outgoing SMS/MMS direct and fallback behavior.

1) Correct MMS fallback settings.

2) Prevent SMS/MMS messages from leaking out under certain
   circumstances when they shouldn't.
Fix UI side of broken MMS fallback.

1) Actually tell the SendReceiveService to send the MMS if it is
   one.

2) Display the correct string (SMS vs MMS) in the fallback dialog.
Fix the "Tap for X fallback" labels.