Fixes #3128 - add json format back to images_controller
Fixes #3144 Remove user_id and inherited_from

Fields user_id in model User and inherited_from in model UserRole are
absolutely superfluous as they are not being used anywhere and result in
unnecessary lines of code and clutter in the database, which contains
NULL values in all cases.
fixes #3129: NoMethodError is no longer being raised when determining the value of a property