Make is_object_stale() a public method
Make is_object_stale() a public method

The _is_object_stale() is meant to be public, so remove the leading
underscore.

Change-Id: Ib4f3be43e563ce3109cceae14ffe69e1976fc4c8

openstack/python-openstacksdk,openstack-infra/shade,dtroyer/python-openstacksdk,stackforge/python-openstacksdk,jsmartin/shade,stackforge/python-openstacksdk,dtroyer/python-openstacksdk,openstack/python-openstacksdk,jsmartin/shade,openstack-infra/shade