Event bus support for belongsTo

When configured:

  belongsTo: function () {
    return {
      project: { collection: projects, bus: EventBus }
    };
  }

will trigger a 'backbone-rel:missing' event on the bus
if a #rel call returns no result.
Configure rel event bus in the backbone model prototype
Bump to version 0.2.2

- Add myself to contributors
- Fix maxim's entry
Address @masylum's comments

- s/false/null
- Move event bus specific stuff to own spec scope
Merge pull request #10 from saimonmoore/feature/event-bus

Event bus support for `belongsTo`