Release 3.1.0

Release to fix Ubuntu packaging.

Change-Id: If0e0cbe926c5b7d1041c6595dae26ff205accea2
Havana: Fixtures: fix keystone branch name

Solve issue: « fatal: ambiguous argument 'stable/havana': unknown
revision or path not in the working tree. »

Change-Id: Id036198175f87dc5bc3d9c3542bdef613d4b9f86
Merge branch 'stable/havana' of https://github.com/stackforge/puppet-nova into havana