Framework: Fixes mms automatic retrieval (2/2)

Currently, in the framework, mobile data connections using APN's can only be
made when the user has explicitly switched on mobile data connections.
This patch allows to automatically open connections to APN_TYPE_MMS mobile
networks. It only opens connections in roaming if the user has selected the
option in Settings.

This allows for the automatically download of mms.

Part 1 in Ibfcbcec8

Patchset 1: Initial patch
Patchset 2: Moved logic to a canSetupData(ApnContext) method
Patchset 3: Checks for system-wide properties if can retrieve mms automatically

Change-Id: I824c7b48d8d534f372e9eccb05fd7e4db226be92