In order to generate a secret which is usable by Ceph
ceph-common must be installed. Rather than forcing the
package when installing the admin node we can install
from the script which generates the secret key.

This install is done silently, at the time of the proposal
creation at which point we use the authtool to create the keys.

Signed-off-by: JuanJose 'JJ' Galvez <juanjose.galvez@gmail.com>
Generate usable and unique secrets for monitor and admin.

Signed-off-by: JuanJose 'JJ' Galvez <juanjose.galvez@gmail.com>