This moves churn to use the gem directly opposed to using cmd line inter...

...face.

Added example configuration changes for churn to the .metrics file

Updated the default tmp directory to keep it under the metric_fu structure.

update tests and code.

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Submitting this PR to start the discussion. Likely needs to be rebased and possibly need some additional test coverage. Please take a look and let me know your thoughts. It has been awhile since I have been in the metric_fu codebase so it will take a bit for me to get my feet wet again ;)