Enhanced MMS configuration prompts and processing.

1) Added a new message status to MmsDatabase to
   signify a pending MMS download which requires
   APN settings.

2) Added a database method to query MMS messages
   based on status.

3) Added login to SendReceiveService for processing
   of MMS pending APN information.

4) Moved all APN/MMS settings into ApnPreferencesActivity
   and transformed PromptApnActivity into a simple
   informational activity.

5) Added logic to check for APN settings on send and
   receive of all MMS (media, group, email) and direct
   user to PromptApnActivity then ApnPreferencesActivity
   if necessary.

6) Vocab/grammar adjustments.