Improve service validation during upgrade Cinder

  * Added modules which allow to check and manage services statuses.

Change-Id: Ib51fd5b65c332aa1d9cae2ebcf9ebb7d510a4df3
Related-PROD: PROD-25157
diff --git a/_modules/cinderv3/lists.py b/_modules/cinderv3/lists.py
index d0bf4e9..5982f06 100644
--- a/_modules/cinderv3/lists.py
+++ b/_modules/cinderv3/lists.py
@@ -5,6 +5,7 @@
 except ImportError:
     from urllib import urlencode
 
+
 @send("get")
 def volume_list(**kwargs):
     """
@@ -27,3 +28,12 @@
     """
     url = '/types?{}'.format(urlencode(kwargs))
     return url, None
+
+
+@send("get")
+def service_list(**kwargs):
+    """
+    Return list of Cinder services.
+    """
+    url = '/os-services?{}'.format(urlencode(kwargs))
+    return url, None