If the profile's default value of a boolean (checkbox) parameter is
true, currently, the ppwizardstart code does not return a false or ""
value if the user unselects the checkbox.  This is because of how
jQuery's serializeArray() serializes form values (it only serializes
"successful" values, which include only checked input checkboxes, not
unchecked checkboxes).  So, we add those values back in the response to
the server (instead of sending "checked" for a checked box, we send ""
-- and this gets correctly interpreted by the python backend).