This command can be used to retrieve or set the ensemble password.

To change this password, you first run `fabric:ensemble-password <new_password>`
and then wait a little while for the new password to get delivered as a
config update to all the fabric nodes. During this time the old password
and new password grant access to the fabric.  Once, all the nodes are updated
then run `fabric:ensemble-password --commit` so that only the new password
is allowed access to fabric.

