See https://www.dokuwiki.org/install:unused_files for more informations

As explained on [this page](https://www.dokuwiki.org/install:upgrade), as the Dokuwiki files (PHP...) and user pages are "mixed" in the same directory, it is better to get the new Dokuwiki version in a separate directory, and then to copy the files.

This way, we won't have conflicts between old volumes and new files in the image. It is safer.

Thanks to the excellent trick here : http://gbayer.com/development/moving-files-from-one-git-repository-to-another-preserving-history/

Improve db-backup image

See merge request !46

Add a testing procedure

See merge request !45

Optimize CI and remove deployment steps, add Mattermost and update Etherpad

See merge request !44