DESCRIPTION
If user hasn't configured a profile photo on their forge instance,
it would point to the default photo of the forge instance, which
might be the same for all users without a profile photo on that
forge instance.
DESCRIPTION
add_user
Adds new user to DB. Implementers must ensure username
uniqueness scoped at forge instance level. When applicable, HTML
link to profile photo may be stored as we..
user_exists
Checks if a user exists in database. Optionally provide hostname
of forge instance to get forge-specific results.