Add support for clarity processing #121

After playing around with creating dynamic classes and monkeypatching them, I think the way forward is to add a processing pipeline to DataDevice. The device will do it's own processing first, then push the data through each stage in the pipeline before returning.
In the first instance, the pipeline can just be a list of functions that take one argument, data, and return that argument. Any object that wants to add to the pipeline can do so by adding a function to the list.