Adds cinder backup functional tests

Adds new tests to cover cinder backup api as well as the needed
json clients.

xml client will be submitted after bug #1270589 is fixed.

Change-Id: I8d40c58eaf0ccd24abf55a212f1177e61ef0a281
Closes-Bug: 1221335
diff --git a/tempest/clients.py b/tempest/clients.py
index c262a20..db0db15 100644
--- a/tempest/clients.py
+++ b/tempest/clients.py
@@ -148,6 +148,7 @@
     VolumeHostsClientJSON
 from tempest.services.volume.json.admin.volume_types_client import \
     VolumeTypesClientJSON
+from tempest.services.volume.json.backups_client import BackupsClientJSON
 from tempest.services.volume.json.extensions_client import \
     ExtensionsClientJSON as VolumeExtensionClientJSON
 from tempest.services.volume.json.snapshots_client import SnapshotsClientJSON
@@ -158,6 +159,7 @@
     VolumeHostsClientXML
 from tempest.services.volume.xml.admin.volume_types_client import \
     VolumeTypesClientXML
+from tempest.services.volume.xml.backups_client import BackupsClientXML
 from tempest.services.volume.xml.extensions_client import \
     ExtensionsClientXML as VolumeExtensionClientXML
 from tempest.services.volume.xml.snapshots_client import SnapshotsClientXML
@@ -212,6 +214,7 @@
                 auth_provider)
             self.floating_ips_client = FloatingIPsClientXML(
                 auth_provider)
+            self.backups_client = BackupsClientXML(auth_provider)
             self.snapshots_client = SnapshotsClientXML(auth_provider)
             self.volumes_client = VolumesClientXML(auth_provider)
             self.volumes_v2_client = VolumesV2ClientXML(auth_provider)
@@ -277,6 +280,7 @@
                 auth_provider)
             self.floating_ips_client = FloatingIPsClientJSON(
                 auth_provider)
+            self.backups_client = BackupsClientJSON(auth_provider)
             self.snapshots_client = SnapshotsClientJSON(auth_provider)
             self.volumes_client = VolumesClientJSON(auth_provider)
             self.volumes_v2_client = VolumesV2ClientJSON(auth_provider)