Add json output to pipe list

[tionis]

I'd like to reliably parse the output of pipe ls.
Currently it's looking something like this:

$ ssh pipe ls
- user-name/channel-name:
  Clients:
    Pubs:
    - 12ab12ab-12ab-12ab-12ab-12ab12ab12ab (key@node@123.123.123.123:4567)

and I thought something like that would be nice:

$ ssh pipe ls --json # for --format json
{
  "user-name/channel-name":
  {
    "clients": {
      "pubs": [
        {"id": "12ab12ab-12ab-12ab-12ab-12ab12ab12ab", "key": "key@node", "ip": "123.123.123.123:4567"}
      ]
    }
  }
}