As an Owner, I can offer my Space to another Member

(User Story, To be Fixed , Priority: High, Test Status: No automated tests yet , Reported By Justin du Coeur, )
Sharing
Summary: This is the beginning of the "Give a Space to someone else" Epic.
You can only give it to another Member of the Space -- otherwise, this is a pretty obvious Spam vector.
I should be able to choose what Role I would like to have in the Space after I give it away, but there should be a message pointing out that the new Owner may change that if they choose.