This change introduces the subcommand `status` to the `airshipctl
cluster` command. The `status` command will iterate over all defined
custom resources in the target path, check their status against the
resources currently in the cluster, and then report results on stdout.
Change-Id: Ieaff6b91fd9055f995c5ba8ce79959356a2a8a02
Relates-To: #73
eecc417495