home: when adding a binding for a user record, use common code for determining automa...

home: when adding a binding for a user record, use common code for determining automatic image path

Make use of the new user_record_build_image_path() helper the previous
commit added to share some code.

Also, let's make sure we update all parsed-out fields with the new data
from the binding, so that the parsed-out fields are definitely
up-to-date.