adding audiosynth submodule\n\nrefs #8; including audiosynth submodule for waveform generation
adding riff player\n\nrefs #8; adding Web Audio API wrapper to preview riffs; adding simple assert library used by riff player
adding promises library\n\nrefs #8; while ES6 promises Promises, we aren't there yet, and we need a consistent implementation
implementing naive riff preview

refs #8; generating a riff will utilize the synth library to play a (buggy) riff preview
migrating to bower