Changing 'death' event to 'exit', as per node's change between version 0.6 and 0.8
Changing checks and logs to use worker.process, as per node's change

For more information please check here: https://github.com/joyent/node/wiki/API-changes-between-v0.6-and-v0.8#changed
Making change work for prior to 0.8 as well as 0.8 and above
Adding a manual test for clustered to demonstrate fix with different node versions
Removing backwards compatibility change
Bumping version to 0.2.0
Merge pull request #2 from domudall/bug/incorrect-event-for-worker-death

Incorrect event emitted for worker death