Make create_server use **kwargs

As we discussed on
http://lists.openstack.org/pipermail/openstack-dev/2015-July/068864.html
All http POST/PUT methods need to contain **kwargs as their arguments.
This patch makes create_server use **kwargs.

Partially implements blueprint consistent-service-method-names

Change-Id: I4b9effc2c68f6a5336eee249ff76686aca8a8480
diff --git a/tempest/stress/actions/volume_attach_delete.py b/tempest/stress/actions/volume_attach_delete.py
index b3753a5..847f342 100644
--- a/tempest/stress/actions/volume_attach_delete.py
+++ b/tempest/stress/actions/volume_attach_delete.py
@@ -39,7 +39,7 @@
         vm_name = data_utils.rand_name("instance")
         self.logger.info("creating vm: %s" % vm_name)
         server = self.manager.servers_client.create_server(
-            vm_name, self.image, self.flavor)['server']
+            name=vm_name, imageRef=self.image, flavorRef=self.flavor)['server']
         server_id = server['id']
         waiters.wait_for_server_status(self.manager.servers_client, server_id,
                                        'ACTIVE')