Renaming Cinder admin client files

This patch renames:

1. tempest/services/volume/base/admin/base_volume_<client name>.py
   into tempest/services/volume/base/admin/base_<client name>.py.
Example:
    base_volume_types_client.py -> base_types_client.py

2. tempest/services/volume/v1/json/admin/volume_<client name>.py
   into tempest/services/volume/v1/json/admin/<client name>.py.
Example:
    volume_hosts_client.py -> hosts_client.py

3. tempest/services/volume/v2/json/admin/volume_<client name>.py
   into tempest/services/volume/v2/json/admin/<client name>.py.
Example:
    volume_quotas_client.py -> quotas_client.py

Partially implements blueprint consistent-service-method-names

Change-Id: I180525ce679a395fdd97a8f2dedb94e4851be43d
16 files changed