Added lower version boundary for netaddr

Versions <= 0.7.4 do not support the "version" parameter on
netaddr.IPNetwork() which is used by Ironic (potentially other projects
as well).

Version == 0.7.5 contains a bug (https://github.com/drkjam/netaddr/issues/2)
that affect the GenericUtilsTestCase.test_get_shortened_ipv6_cidr on
Ironic (potentially other projects as well)

So setting the version of netaddr to be >= 0.7.6 should avoid such issues.

Change-Id: I0218a3bb4f17f1a8101d3fa2d3910fb1645470cf
Related-Bug: #1234672
Require python-cinderclient>=1.0.6

Havana Nova uses cinderclient 1.0.6 APIs to support volume
migration (migrate_volume_completion).

Partial-Bug: #1230925
Change-Id: I5980fb67d99dd49920244513ddd0f282194799a9
Merge "Require python-cinderclient>=1.0.6"
Merge "Added lower version boundary for netaddr"