Create a simulator for generating audio data

[craftyjon]

There should be some testbed code in firemix that can simulate the data coming from the audio processor to use for development and when no audio stream is enabled. We aren't yet sure exactly what the fake audio data should look like, but if we can get the framework in place to test things (maybe by generating white noise FFT) we can iterate on that.

[craftyjon]

Something basic is now in there!