Add API V3 support

Ability to enable or not v3 API in nova-api service.

Change-Id: Id1bf977434d83ac41e8d174ed8a1df0af946cb1c
Signed-off-by: Emilien Macchi <emilien.macchi@enovance.com>
Merge "Add API V3 support"
Merge git://github.com/puppetlabs/puppetlabs-nova