Integrate CodeClimate's test coverage

[umayrh]

Is your feature request related to a problem? Please describe.
We use Coveralls for analyzing test coverage but it would be nice to also enable CodeClimate.

Here are some useful links:

• https://github.com/codeclimate/test-reporter/blob/master/examples/python_examples.md
• https://docs.codeclimate.com/docs/travis-ci-test-coverage#section-travis-ci-single-test-suite-non-parallel-builds

Afterwards, you can add CodeClimate's test coverage badge by adding the following line to README.md:

[![Test Coverage](https://api.codeclimate.com/v1/badges/1b9ae406a6e8b922405a/test_coverage)](https://codeclimate.com/github/umayrh/sparktuner/test_coverage)