Allow building heat-agents image from master
Allow building heat-agents image from master

Previously, the heat-agents image didn't build unless we exported the
OPENSTACK_RELEASE environment variable at build time. This commit
remove that limitation and build the image using RDO master when the
environment variable is not set.

Change-Id: I3a693b978c2ffd00a438fc9e1ff8a9353df8f50b

openstack/tripleo-common,openstack/tripleo-common