Make identity v3 users_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 identity v3 users_client use **kwargs.

Partially implements blueprint consistent-service-method-names

Change-Id: I8b4e2059a9a8d4be1df5aab1de8a4339e97679d2
diff --git a/tempest/api/identity/admin/v3/test_tokens.py b/tempest/api/identity/admin/v3/test_tokens.py
index 89cfd5b..fcf4772 100644
--- a/tempest/api/identity/admin/v3/test_tokens.py
+++ b/tempest/api/identity/admin/v3/test_tokens.py
@@ -32,7 +32,7 @@
         u_email = '%s@testmail.tm' % u_name
         u_password = data_utils.rand_password()
         user = self.users_client.create_user(
-            u_name, description=u_desc, password=u_password,
+            name=u_name, description=u_desc, password=u_password,
             email=u_email)['user']
         self.addCleanup(self.users_client.delete_user, user['id'])
         # Perform Authentication
@@ -62,7 +62,7 @@
         # Create a user.
         user_name = data_utils.rand_name(name='user')
         user_password = data_utils.rand_password()
-        user = self.users_client.create_user(user_name,
+        user = self.users_client.create_user(name=user_name,
                                              password=user_password)['user']
         self.addCleanup(self.users_client.delete_user, user['id'])