updated change log to include ability to use 'undefined' as a configable option
updated change log to include ability to use 'undefined' as a configable option

mesosphere-mergebot/mergebot-test-dcos,mesosphere-mergebot/dcos,kensipe/dcos,dcos/dcos,mesosphere-mergebot/mergebot-test-dcos,kensipe/dcos,GoelDeepak/dcos,mesosphere-mergebot/dcos,dcos/dcos,mesosphere-mergebot/mergebot-test-dcos,dcos/dcos,mesosphere-mergebot/dcos,mesosphere-mergebot/dcos,kensipe/dcos,GoelDeepak/dcos,mesosphere-mergebot/mergebot-test-dcos,dcos/dcos,kensipe/dcos,GoelDeepak/dcos,dcos/dcos,GoelDeepak/dcos