update api documentation

• remove #set_resource_params from Api::BaseController to leave :id param under :id for apipie validations to work
• fix custom apipie validators to return nice errors
• enable apipie validations for bugs to be caught early
• log apipie param errors with info level
• add missing documentation, :search, :order and params from url (:id)
• add missing :allow_nil options in api documentation