Add django-entity as a requirement/installed app.
Basic models layout.
Initial Readme
Convert Readme to ReStructured Text.
Application overview and Source documentation.
Added Medium description to README.
Model doc-strings.
Readme documentation for `Subscription`
Subscription doc revisions.
Usubscription and considerations in README.
subentity_type is nullable.
Spelling corrections.
Corrected example code for Unsubscribe creation.
subentity_type = None comment in doc string.
Merge pull request #1 from Wilduck/models

Models