This means all the sub-subcommands can drop the `image-` prefix,
making them shorter and more fluent.
E.g.,
flux create image policy
rather than
flux create auto image-policy
Signed-off-by: Michael Bridgen <michael@weave.works>
Most commands use either a kind, or a more readable spelling of a
kind, in their output. To make this easier, this centralises the
definition of those names in one place, and lets the command
implementations choose whichever they need.
Signed-off-by: Michael Bridgen <michael@weave.works>
