Test case for cluster-policy operations
Test case for cluster-policy operations

Four test cases added:
1. Cluster attach policy with customized fields;
2. Cluster attach policy with policy not found;
3. Cluster detach policy with policy not found;
4. Cluster update policy with policy not found.

tengqm/senlin,openstack/senlin,Alzon/senlin,tengqm/senlin-container,tengqm/senlin-container,stackforge/senlin,stackforge/senlin,openstack/senlin,Alzon/senlin,openstack/senlin,tengqm/senlin