Work in progress. Don't do this!! Avalon v.4.0 Hasn't been released yet.
In avalon.yml, under streaming, change "url_handler:" to "server:".
Add under streaming: "content_path:" and then the path to your rtmp stream folder.
It should look something like this:
Additional controlled vocabularies are required for Avalon 4. Merge the new version of config/controlled_vocabulary.yml.example with your customizations in config/controlled_vocabulary.yml.