Allows SMI to be bound to multiple MIDI inputs.
Implements attach(inputs), detach(inputs) and detachAll()
Update readme, package.json and bower.json
Merge branch 'master' of https://github.com/kchapelier/SimpleMidiInput.js

# By Kevin Chapelier
# Via Kevin Chapelier
* 'master' of https://github.com/kchapelier/SimpleMidiInput.js:
  Add travis tag