purge repo file when unstacking
purge repo file when unstacking

we remove the download.ceph.com repo during cleanup.

Change-Id: Ia2a62a6307b61623b72dbd7ee391d11cbd27f660
Signed-off-by: Sébastien Han <62d754cc350e84d3b1c32ae79f976f5348e74a40@redhat.com>

ajarr/devstack-plugin-ceph,openstack/devstack-plugin-ceph