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/cmd/javelin.py b/tempest/cmd/javelin.py
index 5d06b90..5566f63 100755
--- a/tempest/cmd/javelin.py
+++ b/tempest/cmd/javelin.py
@@ -869,7 +869,8 @@
             kwargs['networks'] = [{'uuid': get_net_id(network)}
                                   for network in server['networks']]
         body = client.servers.create_server(
-            server['name'], image_id, flavor_id, **kwargs)['server']
+            name=server['name'], imageRef=image_id, flavorRef=flavor_id,
+            **kwargs)['server']
         server_id = body['id']
         client.servers.wait_for_server_status(server_id, 'ACTIVE')
         # create security group(s) after server spawning