Do not add default BT configurations

CM did this recently so I figured we should follow along since this came from them originally

Change-Id: I1bcee310b07526e7163aec9da02a62fe027fbdd8
Add SKT LTE APN

Details per https://jira.cyanogenmod.org/browse/CYAN-1812

Change-Id: I74f264a0bb8b57c8513a103a32b4d6bba5bc8b49
apns-conf.xml: Re-add old StraightTalk ATT apn settings

In some areas, the new StraightTalk ATT apn settings do
not work, requiring the user to re-add the apn settings
on their own, a feat made more difficult by the fact
that StraightTalk only lists the new apn info on their
website

Change-Id: Id02876d4aa461a3ad8e7211ef45f468b6e181036
Correct Tele2 APNs

Per https://jira.cyanogenmod.org/browse/CYAN-1976 Tele2 APNs
are inaccurate and/or outdated.

Change-Id: Iee4672aad87df019cd9b28d50bfb2219e0cb2594
Add Eastlink Wireless APN

Add national and international roaming APNs per
https://jira.cyanogenmod.org/browse/CYAN-1994

Change-Id: Ife2f6ac1b3b712b62ebe71f51d18edd5be462b80
backuptool: Add support for cross-version whitelists

Change-Id: I415eb4d64d693a7e150656802be7f7c4a0e5ab8b