fix for null query params being transmitted as empty strings; this was preventing the use of nulls in list method filters

Author: sanfilip

lib/request.js

@@ -6,6 +6,12 @@ var superagent = require('superagent');
 var FSLASH = '/';
 
 function objectToQueryString(obj) {
+	// Convert null query params to 'null'
+	for (var param in obj) {
+		if (obj[param] === null) {
+			obj[param] = 'null';
+		}
+	}
 	return qs.stringify(obj, { encode: true });
 }