Switching to ubuntu-based images.

Fedora patches various services to use libaudit and gives a fatal error if the audit is not avaialble. However, with the current docker the audit requires a privileged container. To avoid that the code uses less patched executbales from Ubuntu.

Other chnages is that now the tranmission daemon runs directly under the account configured in Dockerfile avoiding the need to use runuser. Plus all the images no longer contain any setuid binaries.