Today key points
1. Rebuild the environment with the new setup.
2. Explore the way the revisions are stored (i.e. to the filesystem), considering the initial storage and set up of default metadata in order to initialize new meta key "subscribers" with an empty list. Lost here much time, thought got familiar with storage package.
3. Add the new constant to the constants/keys.py.
4. Add a new validator for the subscribers meta to the validation.py middleware.
Plans for tomorrow
Store subscribers by item id to meta. Prepare a codereview.
Decide on the fact if a method for sending bulk emails is required and implement if it's the case.