Sharing proposal: federated sharing without acceptance from consumer

[dvh]

It might be interesting to think about a scenario where the consumer doesn't have to accept a providers share offer at all. To have a complete picture of all scenarios I've added the image below as well.

1. Provider sends an invitation to consumer, including the access token.
2. Consumer responds that it has received the invitation and can access the resource from now on.
3. What happens next is up to the consumer. The provider wants to share this resource after all and if it wants to revert access, it can change or delete the access token.

[dvh]

This proposal has been accepted.