only sync the necessary directories in repo-mirror-sync
only sync the necessary directories in repo-mirror-sync

This commit switches the rsync method to only include the necessary
directories to be synced, and thereby excludes all additional
directories not needed by kilo, and speeds up the clone of the
upstream repo mirror (by default rpc-repo.rackspace.com).

Change-Id: I199f5ca876ae2f57ee2f6b3474f476f74829efee
Closes-Bug: #1544035

yanyao/openstack-deployment,yanyao/openstack-deployment,yanyao/openstack-deployment,yanyao/openstack-deployment