Leverage the divingbell perm module to set the etcd data directories
to 700. Prior to this change, they are 755 in Promenade-based
deployments. However, this change is more of a best-practice
technicality than a true value-add, since all the directories
*inside* these data directories already have 700 permissions.
Change-Id: I92290c46441d008f05b40f0c219c1709627d2803