The previous pipeline model required a lot of setup and abstracted away
the processing of records. By passing a HandlerFunc to the consumer we
keep the business logic of processing of records closer to the use of
the consumer.
* Add refactoring note and SHA to README
For situations where we don't want any logs produced by the application.
* Remove references to Logger from README
* Add implementation of DiscardLogger
To allow for different logging endpoints we'll introduce a Logger
interface that will be passed into the pipeline during initialization.
* Add Logger interface
* Use logger interface in pipeline and emitters
