Added a callback handler

Allows the binding of simple callbacks to lifecycle
events of the state machine by specification of initial,
final states, and / or transition names
Added  method to Callback Handler
Removed a short array syntax use as Finite is php 5.3+
Fixed invalids /self usage (PHP5.3)
Add Symfony EventDispatcher as an hard dependency
Merged StateMachine and ListenableStateMachine classes
Removed Stateful object need in CallbackHandler
Added ability to load callbacks via ArrayLoader
Reverted ArrayLoader parameter order to limit BC
Fixed StateMachine event dispatchinh
Added examples
Added StatefulObject to callback arguments
Updated the symfony bundle to manage the new callbacks feature
Merged StateMachine and ListenableStateMachine