apns: remove default- and dun-types for Verizon MMS 31x/48x

Remove the default- and dun-types set on the Verizon MCC=31x
and MNC=48x pairs. This fixes long connection delays to
LTE and EHRPD apns.

It is based on: http://review.cyanogenmod.org/#/c/61711/

Change-Id: Ib39c601cb3610ff972db3849dfc96542f75f5761
apns-conf: Add QUAM APNs

QUAM is a new MVNO in Argentina, using the Movistar network.

Change-Id: Iaf4ee56174a4c886d3f4fbfe2ba27eb39dedfc15