Settings: Specify the WiFi network priority

AOSP has a basic LRU priority for Wi-Fi networks (last connected has more priority).
This changes added the ability of graphically set the priority of any of the configured

This change also introduce new ASS WiFi settings

Wifi country code moved from General to ASS WiFi settings

Thanks a bunch for the idea to Jorge Ruesga

Patchset 2:
- cleanup

Change-Id: I462a99e4668136be1d288bb7ffb19add177c0c76