Adding stock d850 APN file with new ATT Nextgenphone APN.
CM APN file causes issues with MMS.
Adding new ATT APN causes conflicts with existing APN entries.
Deleting existing APNs in apns-conf.xml may cuase issues with other devices.

Change-Id: I1f0c10476d2082cf502b30fd51d512c807021001
Stock AT&T GPS settings.

Change-Id: Ib471ccbb54c3bee124c9ae57cbebd5432ecaef66