Add the field date_sent to keep track of the date a message was sent.
Add the field date_sent to keep track of the date a message was sent.

Change-Id: I7051cf9c0980f82215212b21e0fb6d3b503e43fa

xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base