Added Staff Capabilities to People

The `is_staff` column in the people table allows for separation of
staff and guest members of the auction.

The change of other name fields to ids representing a Person object
should also help reduce duplication in the database.

Be sure to run `rake db:migrate` after pulling this commit.
Added the Specifications Document to the Documentation

The specifications document outlines how the application should work
internal, but not necessarily how a user interacts with the
application. That will be located in
`app/specifications/user_interaction.html`.