added Bmobile Trinidad APN

added from CYAN-5334
Change-Id: Ib1f38b5bf74b41c6f1a39f722c2f16fbdd608e1c
added Boost, Credo & Ting APNs

Also changed name of Sprint MMS apn to be clearer.

Change-Id: Iba70c5882d0c65bc25ebfbf25018739eb800d160
add Virgin Mobile USA apn

Change-Id: Ia016e19b14a173746fddbc5319fac98ca9f188c5