[7.x] Updated docker and CI configs, added tests + bug fixes.

New features

• Refactored Docker Compose configuration to use a single config file (fixes #229, fixes #208, fixes #180, fixes #157 ).
• Added Ahoy config and removed Makefile (fixes #179, fixes #170).
• Added tests for project init, workflow and artefact building.
• Added more descriptions about inner working of Drupal Dev.
• Added example PHPUnit tests.

Fixes

• Fixed up not waiting for DB service to become available (added dockerize).
• Fixed Behat not being able to run single tests.
• Fixed export-db and allow to specify custom file name.
• Fixed DB downalod script from FTP.
• Updated Behat default cache location.
• Fixed several typos in comments.
• Simplified existing commands.

Updates

• Updated Drupal to 7.61.
• Updated FE packages.