Rename cluster scaling command
Rename cluster scaling command

This patch renames the 'cluster scale in' and 'cluster scale out'
commands to 'cluster shrink' and 'cluster expand' respectively.

Change-Id: I70a2172bb08dcdb920922c25d3340ef7afd13a66

stackforge/python-senlinclient,stackforge/python-senlinclient,openstack/python-senlinclient,openstack/python-senlinclient