Altering JsonWarning so that it only warns once. Added spec to confirm that's the case.
Merge pull request #2 from stuliston/json_warning_minor_refactor

Small refactor to json_warning.rb
Updated readme
Moved logging of response body
Adding error messages when set_up or tear_down are not defined, and added no_op as a way to avoid having to use an empty set_up block when there is no data to set up
Added a template for the provider state when no provider state is found