Change database clients to return one value and update tests

Partially implements: blueprint clients-return-one-value

Change-Id: I132115b8e9ec3859469a2b502f862c9270b17884
diff --git a/tempest/services/database/json/flavors_client.py b/tempest/services/database/json/flavors_client.py
index dfb2eb3..c956e27 100644
--- a/tempest/services/database/json/flavors_client.py
+++ b/tempest/services/database/json/flavors_client.py
@@ -27,9 +27,9 @@
 
         resp, body = self.get(url)
         self.expected_success(200, resp.status)
-        return resp, self._parse_resp(body)
+        return service_client.ResponseBodyList(resp, self._parse_resp(body))
 
     def get_db_flavor_details(self, db_flavor_id):
         resp, body = self.get("flavors/%s" % str(db_flavor_id))
         self.expected_success(200, resp.status)
-        return resp, self._parse_resp(body)
+        return service_client.ResponseBody(resp, self._parse_resp(body))