API: get sessions info and get/set proctors

[firasm]

I'd love to be able to have the ability to use the API and get the sessions (and their dates/times/reservations) in a centre for various reasons (analytics, trying to automate flagging to us which sessions are getting full so we can open more).

Another important piece of info about the session is getting (and setting) the session proctor (lead and alternate).

I'm working on using the Deputy API to grab the proctor shifts, and would like to assign them in PT so we can easily know which proctor is assigned to which session. As we grow larger and have more proctors, it's more and more important for us to know which proctors were assigned to which session (and I don't want to give everyone access to Deputy.