Disallow setting /0 for network other than 0.0.0.0

If something like 15.0.0.0/0 is set as an IP address range it ends up
being identical to 0.0.0.0/0 (i.e all access) which I don't think is
the intent of the user when they make the API call.

Change-Id: I3fc05371f461112feae4f1097777fede5fc6b948
Merge "Disallow setting /0 for network other than 0.0.0.0"