getting started with REST API

Implemented in this PR:

/authorizations/[cookie_token]

GET: check user for cookie

/users

GET list users (admin)
POST new user (admin)

/users/[user]

GET user info
PATCH modify user (admin)

/users/[user]/server

POST: start server
DELETE: stop server

There is now a `/home` page which allows start/stop/admin links, and an `/admin` page that is currently empty.