Docker PHP 7.0

[inyono]

• Uses PHP 7.0.33 locally
• Installs composer dependencies in Docker container (see yarn c; install will be run prestart)

TODO:

• [x] Changelog
• [x] Downgrade PHPUnit again for compatibility w/ PHP 7.0
• [x] Run PHPUnit in Docker
• [x] Discussions on profiles still don't work, throw different error though:

  An exception has been thrown during the rendering of a template ("Entity of type 'User\Entity\PermissionKey' for IDs id(123) was not found") in "discussion/helper/default/discussion" at line 49.

[Knorrke]

I think the Exception is caused by #807. https://github.com/serlo/athene2/pull/807/files#diff-4ac32a78649ca5bdd8e0ba38b7006a1eR9

I updated the database dump of permissions, either you need to rebuild the database image or I missed some permissions :-/

[Knorrke]

@inyono did you make changes to docker-compose.yml? Because I don't have the composer container needed for the preinstall

[inyono]

@Knorrke Yep, sorry. Should be there now

[inyono]

Done from my side. Please try it out locally :)