Split base snapshots_client into v1 and v2

This patch splits the base client into v1 and v2 following the model
from the patch at [1] and also migrates those clients to tempest.lib.

[1] https://review.openstack.org/#/c/359442/

Change-Id: I03c254210aeff80173ced68cfa3f3e36ede10d22
diff --git a/tempest/services/volume/v1/__init__.py b/tempest/services/volume/v1/__init__.py
index a7d9270..02eaa7f 100644
--- a/tempest/services/volume/v1/__init__.py
+++ b/tempest/services/volume/v1/__init__.py
@@ -20,13 +20,13 @@
 from tempest.lib.services.volume.v1.hosts_client import HostsClient
 from tempest.lib.services.volume.v1.quotas_client import QuotasClient
 from tempest.lib.services.volume.v1.services_client import ServicesClient
+from tempest.lib.services.volume.v1.snapshots_client import SnapshotsClient
 from tempest.lib.services.volume.v1.types_client import TypesClient
 from tempest.services.volume.v1.json.backups_client import BackupsClient
 from tempest.services.volume.v1.json.qos_client import QosSpecsClient
-from tempest.services.volume.v1.json.snapshots_client import SnapshotsClient
 from tempest.services.volume.v1.json.volumes_client import VolumesClient
 
 __all__ = ['AvailabilityZoneClient', 'EncryptionTypesClient',
            'ExtensionsClient', 'HostsClient', 'QuotasClient', 'ServicesClient',
-           'TypesClient', 'BackupsClient', 'QosSpecsClient', 'SnapshotsClient',
+           'SnapshotsClient', 'TypesClient', 'BackupsClient', 'QosSpecsClient',
            'VolumesClient', ]