Support Kafka 0.7.x and 0.8.x releases.
Add a README since they are great!
Remove extra Chef::Log warn lines and document libraries/chef_kafka.
Add Test Kitchen support.
Fix download URL computation & add testing for producers & consumers.

* Refactor the URL generation code into helpers to simplify the recipe
  code
* Add serverspec tests to ensure that the brokers are listening on the
  service port
* Add serverspec tests to verify kafka's pub/sub
* Verify both 0.7 and 0.8 releases with above tests
Update README and add CHANGELOG.
Merge pull request #1 from hw-cookbooks/support-0.8

Support Kafka version 0.7.x and 0.8.x.