Make security_groups_client 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 security_groups_client use **kwargs.

Partially implements blueprint consistent-service-method-names

Change-Id: I54792d5f80291b5bdd2f7896e08ac741597c1877
diff --git a/tempest/api/compute/base.py b/tempest/api/compute/base.py
index 33442b2..2126787 100644
--- a/tempest/api/compute/base.py
+++ b/tempest/api/compute/base.py
@@ -222,8 +222,8 @@
         if description is None:
             description = data_utils.rand_name('description')
         body = \
-            cls.security_groups_client.create_security_group(name,
-                                                             description)
+            cls.security_groups_client.create_security_group(
+                name=name, description=description)
         cls.security_groups.append(body)
 
         return body