- We are still using ruby 2.7 so we can't bump to latest version
  everywhere

- Meson generates .tar.xz release tarball, we need to be able to support
  it with moka release manager

- Update to latest working version for some of our old dependencies

- Add a Gemfile.lock for reproductible deployments

- Rephrase some sentences, add https links etc

- Update to sinatra 2 (it works)
- Remove obsolete sass gem, use directly a .css
- Remove jeweler and Rakefile, we don't need to create .gem file

- Add mysql adapter
- Tested with ruby 2.3 and 2.5; seems to works fine

- By adding Encoding.default_external = 'UTF-8', moka used with
passenger now support UTF-8 special characters in releases notes without crashing.

- This way it's easier to setup moka !

This allows removing branches again.

The "receive.denyNonFastforwards = true" will forbid ff commits,
and the hooks have a rule to avoid removing tags and special branches.

This way the releaser is can descide is this needs to
be included in the notes.