Daily/hourly crawler for subscription- & notification service(s)

[uklotzde]

Subscriptions and notifications are a separate domain that is independent of the geographical mapping of places and events.

• All subscriptions should be handled by a separate service that periodically polls OpenFairDB for changes (hourly, daily). Even independent subscription services for different use cases are possible. Decouple post-processing from requests for Notifications #166

• OpenFairDB should provide extension points in the form of an API that enables this decompositions. One request is already available: Query recently changed entries #198

• All subscriptions and notifications should be removed from OpenFairDB. This make Extend subscription and notification service #194 obsolete.

[wellemut]

Seems to be a duplicate of: #194

[wellemut]

This is an alternative: #166

[wellemut]

This is going to be solved soon by @magdaddy . Its exactly the why he is doing it by using the "recently changed api" #258 (comment)