Reached 3.0.0-alpha

- Fixed #12 terminology unification
- Removed RENDERERS, fixed #11
- @keyapril added a way of solving #9 , which is to delegate custom events
  of bricks
- Fixed #6 brix/app api
- Fixed #5 the load, render and bind procedure, a.k.a. the lifecycle of
  brick instance
- Fixed #3 the promised procedure
- Fixed #2 app.boot and Brick#boot logic