User defined wifi/usb tether network. [2/2]

Enables users to select from a list of predefined networks
for use as the tether network, overriding the built-in networks.
This is useful, for example, where OpenVPN is in use with
routed setup.

Conflicts:
	res/values/custom_arrays.xml
	res/values/custom_strings.xml

Change-Id: I24749a28662e160c60ae7fa07b4c6542d82cdf7f

Conflicts:
	res/values/liquid_strings.xml
	res/values/slim_arrays.xml