Make create_server_group 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_group use **kwargs.

Partially implements blueprint consistent-service-method-names

Change-Id: I543b61fe8e87faa219eb5485cf4fcb0f8e926c14
diff --git a/tempest/api/compute/base.py b/tempest/api/compute/base.py
index b0fdbac..ec2192f 100644
--- a/tempest/api/compute/base.py
+++ b/tempest/api/compute/base.py
@@ -246,8 +246,8 @@
             name = data_utils.rand_name(cls.__name__ + "-Server-Group")
         if policy is None:
             policy = ['affinity']
-        body = (cls.server_groups_client.create_server_group(name, policy)
-                ['server_group'])
+        body = cls.server_groups_client.create_server_group(
+            name=name, policies=policy)['server_group']
         cls.server_groups.append(body['id'])
         return body
 
diff --git a/tempest/services/compute/json/server_groups_client.py b/tempest/services/compute/json/server_groups_client.py
index 33501fb..62258d3 100644
--- a/tempest/services/compute/json/server_groups_client.py
+++ b/tempest/services/compute/json/server_groups_client.py
@@ -22,18 +22,13 @@
 
 class ServerGroupsClient(service_client.ServiceClient):
 
-    def create_server_group(self, name, policies):
+    def create_server_group(self, **kwargs):
         """
         Create the server group
         name : Name of the server-group
         policies : List of the policies - affinity/anti-affinity)
         """
-        post_body = {
-            'name': name,
-            'policies': policies,
-        }
-
-        post_body = json.dumps({'server_group': post_body})
+        post_body = json.dumps({'server_group': kwargs})
         resp, body = self.post('os-server-groups', post_body)
 
         body = json.loads(body)