Change basic server client methods to return one value and update tests

This includes create_server, update_server, get_server, delete_server and
also some helper methods such as create_test_server

Partially implements: blueprint clients-return-one-value

Change-Id: I8e1fba7a31a0ed27e683dacd9a8e763759552c11
diff --git a/tempest/api/telemetry/base.py b/tempest/api/telemetry/base.py
index dc7a8f5..7ec0646 100644
--- a/tempest/api/telemetry/base.py
+++ b/tempest/api/telemetry/base.py
@@ -62,12 +62,12 @@
 
     @classmethod
     def create_server(cls):
-        resp, body = cls.servers_client.create_server(
+        body = cls.servers_client.create_server(
             data_utils.rand_name('ceilometer-instance'),
             CONF.compute.image_ref, CONF.compute.flavor_ref,
             wait_until='ACTIVE')
         cls.server_ids.append(body['id'])
-        return resp, body
+        return body
 
     @classmethod
     def create_image(cls, client):