Cleanup client.speaker and add additional tts speakers

This is the second chunk of split up pull request jasperproject/jasper-client#124.

I've added svox-pico-tts and google-tts. Pico TTS is the old Google OpenSource TTS Engine. Try it, it's much better than espeak!

Also, get rid of aplay and use pyaudio instead (pyaudio is a dependency anyway, so why rely on an external tool that might not be installed)
Unused import.