Add initial cluster-template-* commands to CLI
Add initial cluster-template-* commands to CLI

list - list cluster templates
delete - delete a cluster template

Implements: blueprint python-savannaclient-cli
Change-Id: I33b638245e5b1f1db27e514f4953b4c13e18a5e7

citrix-openstack-build/python-saharaclient,citrix-openstack-build/python-saharaclient,openstack/python-saharaclient,citrix-openstack-build/python-saharaclient