Deny json access

I don't really know how "hacky" the solution is. Basically I'm checking to see if the query for the page has anything in the "QUERY_STRING" header. Since the only actions we made that use these pages are for autocomplete, only those requests will have anything in the "QUERY_STRING" header. Otherwise, it's just a plain GET request which we want to block. At this moment, I don't know another way to differentiate between requests coming through our autocomplete gem/AJAX and requests coming through normally.
Prefer double-quoted strings unless you need single quotes to avoid extra backslashes for escaping.