Move "activation finished" message to after the reboot
Don't ask for passwords

Charon is supposed to be non-interactive, so asking for passwords
(usually due to some SSH agent problem) is annoying.
charon check: More detailed info

‘charon check’ now prints a table showing whether each machine exists,
is up and is reachable via SSH, its load average and all systemd
services that are in a failed state.
charon check: Colourful output
charon check: Check all machines in parallel.
charon check: Check whether EBS volumes are still attached
charon check: Set the exit status to reflect the result of the checks

An exit status of 0 means that all machines are fine.  Otherwise, it's
a bitwise OR of the following values:

 1 - some machine does not exist
 2 - some machine is down
 4 - some machine is not reachable
 8 - some disks are in trouble
16 - there are systemd units in a failed state
charon check: Add --include / --exclude flags