Refactored validation system to use the EventDispatcher.
Use the EventDispatcher in AbstractControllerValidationTest.
Inlude the correct namespace for the ValidationException.
Changed validation event name.
Added a new MaxSizeValidationListener.
Removed old ValidationTests. Need to be reintroduced.
Added validator to validate allowed extensions.
Added validator to validate disallowed extensions.
Made all the validators non-public.
Republished event listener, as otherwise they won't be dispatched.
Added newline in ValidationListener.