Provide search by presence or absence of a field.
Process search fields as JSON to be sent via AJAX request.
Change search query format, encapsulated inside a filtered field,
and separated on query and filter, giving that the query part
searches for values (as before) and the filter part filters for
presence or absence of certain fields.
Change the query= and query methods in SearchQuery model to
receive and process data as JSON instead as a form request.
Change the buttons to link, to prevent unwanted form submition,
in the search_queries views.