Add support for downloading and reporting Code Climate coverage reports

[jrgriffiniii]

This was a manual process introduced into https://github.com/samvera/hydra-editor/pull/168/files#diff-1d37e48f9ceff6d8030570cd36286a61R83 for samvera/hydra-editor#168.

[cjcolvar]

We've got an example of this for parallelized tests in avalon: https://github.com/avalonmediasystem/avalon/blob/develop/.circleci/config.yml#L86-L141