Improve CinderFixtureNewAttachFlow
Improve CinderFixtureNewAttachFlow

This does three things:

1. Implements the attachment_complete method in order to
   fail if code is trying to complete an attachment that
   does not exist.

2. Adds logging in the various attachment CRUD methods to
   aid in debugging test failures.

3. Mirrors the method signature for is_microversion_supported
   to make sure code is at least calling it properly.

Change-Id: If6a36d23768877bfa820ed44b610bfb113df5464

openstack/nova,rahulunair/nova,mahak/nova,klmitch/nova,mahak/nova,openstack/nova,klmitch/nova,rahulunair/nova,rahulunair/nova,klmitch/nova,openstack/nova,klmitch/nova,mahak/nova