Add test for #70 and Signal#countListeners method used by the test.
Fix #70; resets component operation handler when an Entity is
removed from an engine.
Fix ordering of arguments for test.
Update AUTHORS file.
Remove count method only used in test
Update "resetEntityCorrectly" test to loop over multiple entities.
Add removeAllListeners method to Signal
Update PooledEngine to correctly reset entity signals and
update test accordingly.
Merge pull request #72 from SgtCoDFish/master

Fixes #70: PooledEntity: entity not fully reset