frameworks/base overlay: add MMS UA and UAProfUrl strings for maguro

MMS related strings to be returned by the newly added TelephonyManager APIs.

Change-Id: I435987ac0128298f724a2e672ca472ce3349e577
Increase the SMS/MMS thread history limit

Change-Id: Ibaa186225c61f2fa2298c7a893e99ae7398a2678