Full response for Volume ExtensionsClient methods

Provide the entire response object for all methods of the
ExtensionsClient

partially implements: blueprint method-return-value-and-move-service-clients-to-lib

Change-Id: Ic31d3a9a7c92f46f44cb5ce340cde195ff7318ce
diff --git a/tempest/api/volume/test_extensions.py b/tempest/api/volume/test_extensions.py
index 17db45f..cce9ace 100644
--- a/tempest/api/volume/test_extensions.py
+++ b/tempest/api/volume/test_extensions.py
@@ -30,7 +30,8 @@
     @test.idempotent_id('94607eb0-43a5-47ca-82aa-736b41bd2e2c')
     def test_list_extensions(self):
         # List of all extensions
-        extensions = self.volumes_extension_client.list_extensions()
+        extensions = (self.volumes_extension_client.list_extensions()
+                      ['extensions'])
         if len(CONF.volume_feature_enabled.api_extensions) == 0:
             raise self.skipException('There are not any extensions configured')
         extension_list = [extension.get('alias') for extension in extensions]
diff --git a/tempest/services/volume/json/extensions_client.py b/tempest/services/volume/json/extensions_client.py
index 1098e1e..5744d4a 100644
--- a/tempest/services/volume/json/extensions_client.py
+++ b/tempest/services/volume/json/extensions_client.py
@@ -25,7 +25,7 @@
         resp, body = self.get(url)
         body = json.loads(body)
         self.expected_success(200, resp.status)
-        return service_client.ResponseBodyList(resp, body['extensions'])
+        return service_client.ResponseBody(resp, body)
 
 
 class ExtensionsClient(BaseExtensionsClient):