wrap entry point to prepareValue to only accept 1 arg

lib/utils.js

@@ -103,6 +103,10 @@ function normalizeQueryConfig (config, values, callback) {
 }
 
 module.exports = {
-  prepareValue: prepareValue,
+  prepareValue: function prepareValueWrapper (value) {
+    //this ensures that extra arguments do not get passed into prepareValue
+    //by accident, eg: from calling values.map(utils.prepareValue)
+    return prepareValue(value);
+  },
   normalizeQueryConfig: normalizeQueryConfig
 };