Allow waiting for a command to be something

[withinboredom]

So instead of writing:

{
  "command": ["while","[","$(hub","ci-status","HEAD)","!=","'success'","];","do","echo","'waiting for status checks'",";","sleep","1",";","if","[","$(hub","ci-status","HEAD)","==","'failure'","];","then","echo","'oh snap, we cannot release this';","exit","1;","fi;","done;"]
}

I can write:

{
  "command": ["hub","ci-status","HEAD"],
  "waitfor": {
    "output": "success",
    "exit_code": 0,
    "timeout": 100000,
    "fail": {
      "exit_code": 1
    }
  }
}

or something to that effect...

[withinboredom]

Seems like the perfect case for a tool plugin...