Added blurb about the change in worker polling mechanism

I've left a placeholder [here](https://github.com/jasonbosco/coffee-resque/compare/technoweenie:master...jasonbosco:master#L0R61) and [here](https://github.com/jasonbosco/coffee-resque/compare/technoweenie:master...jasonbosco:master#L0R78) for the new version number. I wasn't sure if you'll be bumping the version to v0.1.9 or something else.

Reference: https://github.com/technoweenie/coffee-resque/pull/34#issuecomment-20366895