Hivemind process exits 0 regardless of child process status

To my understanding, the parent process should exit with the same status as the child process it's running (if there's only one child process maybe), or some other non-zero status.

Example:

`Procfile`:
```
test: exit 1
```

```bash
❯ hivemind -l test
test | Running...
test | exit status 1

❯ echo $?
0
```

Thanks in advance!