Store past officers along with current officers

* Adds 'old_officer' role to indicate a past officer
* Modifies users table to store last year the person was an officer
* Improvements to fake data generation: use real titles for fake profiles
* Refactor officer page to prioritize executive officers and display past officers
* Utility function in setup.sql script to automatically make a user a webmaster

Fixes #202 
This would be a good place to use `filter_by` rather than querying all objects.