Sync latest network_utils module from Oslo

Syncs the latest network_utils from Oslo to help simplify the fix
needed for bug #1216247. Also adds network_utils to
openstack-common.conf.

This also includes the following commits to network_utils:

897aa7c urlsplit issues with IPv6 addresses in python26
35dc1d7 py3kcompat: remove
12bcdb7 Remove vim header
4c22556 Use py3kcompat urlutils functions instead of urlparse
0bf03b7 Add network_utils.urlsplit
e456727 Remove useless logging in networks_utils
7119e29 Enable hacking H404 test.

Change-Id: I63325c9b677c2192d24e7eb73adac272bffd4e0b
Merge "Sync latest network_utils module from Oslo"