Test audio with add-test-audio.py and stream-test.py

Adding audio and scripts to better automate the testing process. Lots more could be done, but this here saves lots of time for basic tests.

```
vagrant up
vagrant ssh
cd roundware-server/scripts
./add-test-audio.py
./stream-test.py
```

Then
```
./stream-test.py
```
can be used many more times. Be interesting to make it more interactive, but that's for the future.