Add "query_string" property to http_request object...

contains the raw query string as passed to the script.

Add "post_data" property to http_request object for POST requests...
contains the raw POST data as passed to the script (if any)

Add "request_string" property to http_request object...
contains the full raw URI from the request line

Clean up the adding of properties to the http_request object by using
js_add_request_prop()  (Various subs no longer fail if a property
cannot be defined)