I should be able to easily re-fetch a Shared Link

(User Story, Closed -> Fixed, Priority: Critical, Test Status: No automated tests yet , Reported By Justin du Coeur, )
Invites
Summary: Currently it's easy enough to create a Shared Link -- but once you leave that page, it's impossible to get that URL again. That's idiotic.
We should call a spade a spade, and merge the Shared Link and Custom Role functions, since they're really the same thing. Each Custom Role should have an Edit tab, that lets you (among other things) fetch a Shared Link for inviting people with this Role. Pressing that button should add the Roles.IsOpenInvitation(true) flag on the Role (if it isn't there already), and use NotifyInvitations.generateShareableLink() to generate the correct Link. See SecurityFunctionsImpl.makeShareableLink() for a model; this will be quite similar, and might share some code.