Proposal for notifications endpoint

[dvh]

In our proposals we let the providing service maintain control over 'their' share. In the end, they are the owner and are able to revert access etc. By that I mean that when provider A wants to unshare a resource with consumer B, we should not rely on B's implementation of 'unshare' to change permissions. Instead, the 'unshare' feature can be simply removing or changing the access token on the provider side, making the resource unavailable for the corresponding consumer.

However, to make life easier for the consumer we should provide a notification functionality to notify trusted services of certain events. If we do this in a generic way, we might use this feature for (future) different notifications as well.

[dvh]

This proposal has been accepted.