part 2 of LTE toggle support

Change-Id: I21050a18269c15be054e35f5f75fd339e1f270f5
Mobile Network Battery Saver Mode

When idle (screen off) switching to 2G can help extend
battery life as 2G generally uses less power than 3G or LTE.

    + 30 seconds after screen turns off, set network type to 2G
    + If a music player is active (playing), do not set network to 2G
    + When device is unlocked, reset to orignial network type

Settings -> More -> Mobile Networks -> Battery saving mode

Change-Id: Ief8f203f157af3a1484966d43fcc07fd160e4ad7
Revert "Mobile Network Battery Saver Mode"

This reverts commit 5a6dd03c484713020352d9a4d1a8115d8a587004.
Revert "Telephony: Mobile Network Battery Saver Mode"

This reverts commit 5d40677bd17e8c4602e8b974278f9c4e4d1aec7f.
Mobile Network Battery Saver Mode

When idle (screen off) switching to 2G can help extend
battery life as 2G generally uses less power than 3G or LTE.

    + 30 seconds after screen turns off, set network type to 2G
    + If a music player is active (playing), do not set network to 2G
    + When device is unlocked, reset to orignial network type

Settings -> More -> Mobile Networks -> Battery saving mode

Change-Id: Ief8f203f157af3a1484966d43fcc07fd160e4ad7