refactor to avoid looping over vifs twice

Change-Id: I95e2f68cfa2378586bb6f0af1457f78f620a0967
Fix for fake_get_instance_nw_info()

Change-Id: I3d658cc160fc2e140c7ce76d86cac982d60b1848
Reduce db lookups during get_instance_nw_info()

Change-Id: I1e9e55c3c615040ef2181b92db16a2d189e88f43
Make db.fixed_ips_by_virtual_interface() join by floating_ips

Change-Id: I651ea84b03789b6fa89b85e6d1304ba1d8816a2a
Remove nova_ipam_lib.py

Change-Id: Id7750786916d60d6d07e91d5338a6539a7f55041