Add option to directly reply the reply of a single host

[nritsche]

For https://github.com/chime-experiment/Infrastructure/issues/154 coco needs a report option to simplify a reply from a single host to just that reply, without the typical coco report overhead:

["cn3g2:12048", "cn3g8:12048", "cs8g0:12048"]

instead of

{"success": true, "blocklist": {"http://coco/": {"reply": ["cn3g2:12048", "cn3g8:12048", "cs8g0:12048"], "status": 200}}}

[andrerenard]

Can we also remove the port number on the host?

[nritsche]

Can we also remove the port number on the host?

Yes, but that should probably a completely separate option: #218