Add support for Composer (PHP package manager)
At the moment it is possible to use every single project as a repository of type vcs. If a project needs many dependencies which are not on packagist.org, every package needs a repository configuration and a dependency configuration. Or a separate satis installation is necessary. With a build in composer repository one single line would allow to get the projects from GitLab. The build in repository should link to the zip archives of the tags for fast file transfer.