Fixed long presses behaving incorrectly.

Fixed long presses causing events not to be consumed by the
GestureDetector. This issue was causing the GestureDetector to return
false in touchDragged and touchUp whenever a longPress returned true
resulting in unexpected behavior which one would likely only notice when
chaining InputProcessors in an InputMultiplexer.
Merge pull request #438 from Jadems/master

Fixed long presses being handled incorrectly.