Bump to Nova v2.1
Bump to Nova v2.1

1.What is the problem:
The nova team has decided to remove nova v2 API code completely.
And the patch have been merged.

Refer to https://review.openstack.org/#/c/311653/

2.What is the solution to the problem:
To fix the issue, we should bump to use v2.1 ASAP.

3.What is the purpose of this patch set:
The v2.1 API has been used as the default API since Liberty and legacy
v2 API has been marked as deprecated. Based on this, we bump to use
v2.1 ASAP for better development of the Tricircle.

Change-Id: I375a6509cf80613804f3fff19054d699dc5d8a1b

stackforge/tricircle,openstack/tricircle,openstack/tricircle,stackforge/tricircle