Refactor the hooks/payload handling

More agnostic Payload data models will help in adding more webhooks.
Refactor the event and actions workflow

Clean up the names and concerns of the project.
Hook reception and dispatched is now based around a few core concepts:
* A Payload class is parsing the data received from a Webhook endpoint and extracts data from it
* Extracted payload data is composed of Event objects identified by their type
* Each event can result in one or multiple operations defined in Action classes
Cleanup initializers naming