Sharing codes for volumes list tests

1. merge the common tests between v1 and v2, and set its
   default value for v2.
2. make volumes v1 list tests inherits common tests
3. leave volumes v2 specific tests in direcotry 'tempest/api/volume/v2'
4. delete BaseVolumeV2Test

Partially implements: blueprint cinder-v2-api-tests

Change-Id: I7cecbde9543c441a2f3478941f85625755aabf7f
Add a skip for bug #1334368

Trust checking for 204 response is incorrect to support httpd based
deployment because mod_wsgi could translate a HEAD call to GET.
According to HTTP spec HEAD needs to respond with the same
response as GET.

This disables the trust check for HTTP 204 for
changeId: I13ce159cbe9739d4bf5d321fc4bd069245f32734

Once the changes to Icehouse and Juno (master) are accepted, this
can be modified to look for HTTP 200 and re-enabled.

Change-Id: I5e7d7dab2fc1432888bf8c691cae9f2109ac2fec
Partial-Bug: #1334368
Merge "Sharing codes for volumes list tests"
Merge "Add a skip for bug #1334368"
Merge branch 'master' of https://github.com/openstack/tempest