Play a song from the queue by its index.

Adds index specification to the play command

```Shell
python sonoshell.py 10.x.x.x play 4
```

plays track 4 from the queue , verify that it plays the correct by checking
```Shell
python sonoshell.py 10.x.x.x queue
```

I'm posting this now because I wanted it right now, but if the new project repo for this client is set up in near future, I can post it there instead.