Access levels and login decorator updates

- Logging in now sets your access level. Currently, this is set to the
  maximum access level of all of your offices. This does not check that you
  are still active, which should be changed (???). If you have no office,
  then you are access level 2. Access level 1 is for on-campus-network, and
  access level 0 is for random people.
- Login decorator updated to use access levels. If a page specifies a
  specific access level, then only users with that level or higher can
  access it. Alternatively, if a page specifies a specific username, then
  that user is able to access it (regardless of access level).

TODO: Set access level to 1 if someone is on a campus network.
TODO: Only set the access level for ACTIVE offices?