documentation: style and coverage integration

[bradfordcondon]

I should adapt my blog posts into the RTD here https://www.bradfordcondon.com/2018-12-11-drupal_code_coverage/

I doubt that we'll provide a more automated solution for these things...

[bradfordcondon]

• stub out a .codeclimate.yml file -- easy and generic
• modify phpunit.xml to include proper files for tetsting
• modify travis.yml to build the coverage report and send it to code climate

step 1 is fine for changing the test suite setup. two is harder: if you have code in custom locations, you'd have to configure it yourself (ie not in .includes). It could recurisvely search for .php and .inc files and add those, i guess..
step 3 is easy to automate EXCEPT you need your code climate key in there, so we would prompt user to add themselves, or collect it on setup.