Real composer patches format

[szeidler]

Here's my initial work on making drupal_tests compatible with the correct composer-patches format, like reported in #47 .

Includes changes:

• Use the proper composer-patches format
• Look for any inline patches in the composer.json of the module
• Look for external patch files defined by patches-file in the module
• Fallback check for an existing patches.json like it was before, no matter if it was defined in the module's composer.json

I added a test module repository at https://github.com/szeidler/drupal_tests_composer_patches . CircleCI: https://circleci.com/gh/szeidler/drupal_tests_composer_patches

I'm looking forward for your feedback.

[deviantintegral]

• circleci config validate Error: Error parsing config file: yaml: line 9: mapping values are not allowed in this context

Not sure why this failed, as you haven't touched this file. I'll take a look.