Merge pull request #4 from soundsplosion/tg

Added a basic instrument to Rhombus, which is triggered by calls to insertNote().
Add a demos folder
Merge pull request #5 from soundsplosion/jy

Add a demos folder
Added a basic noteOn() and noteOff() interface to the default instrument.
Added worker that drives scheduler
Set up gulp based build system, split library into seprate files
Added note scheduling, made instrument polyphonic