First working version, supports phpunit (using build matrix):
- php72 (lowest), running mysql.
- php74 (highest), running postgres.
Also verifies that the branch has been "gruntified" and there
isn't any missing change (build js/css files).
TODO: Verify the remaining checks currently in .travis.yml, namely:
- CITEST
- Add caching
- Better health-check for DB images.
- Support from the tracker (satus badges and enable check).
- Support from CiBoT (status and enable check).
- Consider moving both the common setup (git, composer...)
and the database (mysql, postgres) to own actions for
easier tweaking.
