`juju info` should provide a way to specify revision

[Haw Loeung]

Hi,

Trying to get info on a charm, landscape-client, and prior revisions but there isn't a way to do so with `juju info`:

| juju info landscape-client --revision 48 --channel stable --series xenial
| ERROR option provided but not defined: --revision

Only way is to deploy it with:

| juju deploy landscape-client --revision 48 --channel stable --series xenial landscape-client-old

Then inspect the changes in `/var/lib/juju/agents/unit-landscape-client-old-0/charm` on the unit itself.

Would be nice to be able to provide a `revision` so we could see the date at which that revision of a charm was published.

[Vitaly Antonenko (anvial)]

Thx, this is a reasonable suggestion.