bloc-v0.3.0

Feature parity with dart

• BREAKING: rename BlocDelegate -> BlocObserver
• BREAKING: remove BlocSupervisor
• BREAKING: transformEvents returns Observable<Transition<Event, State>>
• BREAKING: remove initialState in favor of super constructor
• BREAKING: rename Transition state to currentState
• feat: add transformTransitions
• refactor: internal implementation improvements
• docs: add inline documentation and return types