Releasing version 1.1.0

 - Added ability to change tempo of a song after it's been loaded and also while it's playing. Fixes #16
 - Changed `Conductor.setOnFinished()` to `Conductor.setOnFinishedCallback()` to fit current API.
 - Changed `createSound()` to `createNote()` for instrument packs. It fits more into the nomenclature of the app.
 - Added ability to change buffer length of notes. Probably not a good idea to play around with this.
 - Updated README.me with missing API.
 - Cleaned up some variable names.