[2/2] Settings: Add custom periods for data usage measurement

Change-Id: I815f6a773375a855514bc9a6517f292ffcc157a2

Conflicts:
	res/layout/data_usage_cycle_editor.xml
	res/values/custom_arrays.xml
	src/com/android/settings/DataUsageSummary.java
	src/com/android/settings/net/NetworkPolicyEditor.java