Softbank carrier overlay that fixes Mms User Agent for both Mms.apk & Hangouts

This forces set UA string to Nexus5 for SoftBank MCC:440 MCN:20.
Tested send/receive & confirmed working by yours truly.

Change-Id: I1831c329eb38507a957111052bb5f56350c49361
Merge remote-tracking branch 'PA/kitkat' into kitkat-legacy