Create an installer package

It would very helpful to provide an installer for Decidim. I think there are 3 possibilities: 1. A DEB package just like Gitlab does with its omnibus packages: https://docs.gitlab.com/omnibus/manual_install.html This system allows to install everything but it changes the current host system. It's good when installed in a fresh machine. 2. Docker, that's a very containerized method but it requires docker and certain sys-admin skills. A good example is KoboToolbox, with provides a docker production ready installation: https://github.com/kobotoolbox/kobo-docker 3. A Snap package, although created by Ubuntu it can be installed elsewhere, it may be a very interesting format as it allows self-updating and is a semi-containerized solution. It doesn't mess with your current software installed but it can package all the necessary components and the maintainer doesn't need to care about the host system. NextCloud uses this method: https://github.com/nextcloud/nextcloud-snap