Expose to auth_* whether they are being used for site or election
Auth_password: wait for upload of db when used in an election

When the login service is used for the first time, it asks for a
password database. For now, it is the administrator's responsibility
to do it before advertising the election.
Add password authentication to demo election
Being featured is not an intrinsic property of an election

Drop the property from WEB_PARAMS and import_election arguments. It is
up to the caller of import_election to call add_featured_election
afterwards.