Make volume volume_client to use **kwargs-part2

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 volume volume_client use **kwargs for all remaining
methods.

Partially implements blueprint consistent-service-method-names

Change-Id: I7d65b18fb9f642d7b78b6474eb922c3382daab3e
diff --git a/tempest/api/volume/test_volumes_extend.py b/tempest/api/volume/test_volumes_extend.py
index 78f5571..ed1e5c5 100644
--- a/tempest/api/volume/test_volumes_extend.py
+++ b/tempest/api/volume/test_volumes_extend.py
@@ -32,7 +32,7 @@
         # Extend Volume Test.
         self.volume = self.create_volume()
         extend_size = int(self.volume['size']) + 1
-        self.client.extend_volume(self.volume['id'], extend_size)
+        self.client.extend_volume(self.volume['id'], new_size=extend_size)
         self.client.wait_for_volume_status(self.volume['id'], 'available')
         volume = self.client.show_volume(self.volume['id'])['volume']
         self.assertEqual(int(volume['size']), extend_size)