Added output from the ssh command to the original opts.session

Each element of the ops.session array will have `ops.session.out`
corresponding to the output of the ssh command. After the commands
are executed via `exec`, the array will look something like this:

```
opts.session= [ { op: 'exec',
    command: 'hostname',
    out:
     { code: 0,
       signal: undefined,
       stdout: 'Some output\n',
       stderr: '' } },
  { op: 'exec',
    command: 'uptime',
    out:
     { code: 0,
       signal: undefined,
       stdout: 'Other output\n',
       stderr: '' } } ]
```