Provide work around for 0.0.0.0/0 ::/0 for ipset

Provide work around for 0.0.0.0/0 ::/0 for ipset

Previously, the ipset_manager would pass in 0.0.0.0/0 or ::/0 if
these addresses were inputted as allowed address pairs. This causes
ipset to raise an error as it does not work with zero prefix sizes.
To solve this problem we use two ipset rules to represent this:

Ipv4: 0.0.0.0/1 and 128.0.0.1/1
IPv6: ::/1' and '8000::/1

All of this logic is handled via _sanitize_addresses() in the ipset_manager
which is called to convert the input.

Change-Id: I8c6a08e0cf3b5b5386fe03af9f2174c666b8ac75
Closes-bug: 1461054