Added very simple demo of tts functionality.

Basically, this repeats everything you say to it using stt and then
tts. For this to work you need to have speak.js downloaded from
https://github.com/kripken/speak.js. The speakGenerator.js,
speakClien.js, speakWorker.js must be in the folder containing this
.html file. Then, as before, the folder containing all of these files
must be run as a server using python (python -m SimpleHTTPServer <port
number>).