Working Sequencer and Instrument classes. see #48

AudioNotification creates an instrument and a sequence.
Polyfills for Safari's outdated API method names
Generating tone based on name. Added Audio Bus and effects
AudioAvatar notifications on other user vote. #48
route audionotification through a bus for effects. #48
Adding VCA and EnvelopeGenerator for amplitude envelopes. #48
ensure audio notifications happen on idea and IdeaThread creation. closes #48
Merge pull request #55 from cremalab/audio-notifications-48-rb

Audio notifications