Feature/service instance scope

Some feature work in the Services team backlog to enforce a new scope necessitated much larger changes in the structure of authentication/authorization code. Because the change is so big, we were hoping for a code review from a pair on the Runtime team.

Our commit messages attempt to describe in detail how each commit refactors the existing behavior. If you have any questions, come find David Sabeti, Nick Calugar, or Alex Stupakov.