findOrCreate does not modify inputs

This helps when making spy assertions about what arguments findOrCreate
was called with.

lib/dao-factory.js

@@ -567,16 +567,21 @@ module.exports = (function() {
   DAOFactory.prototype.findOrCreate = function (params, defaults) {
     var self = this;
 
+    var where = {};
+    for (var attrname in params) {
+      where[attrname] = params[attrname]
+    }
+
     return new Utils.CustomEventEmitter(function (emitter) {
       self.find({
-        where: params
+        where: where
       }).success(function (instance) {
         if (instance === null) {
           for (var attrname in defaults) {
-            params[attrname] = defaults[attrname]
+            where[attrname] = defaults[attrname]
           }
 
-          self.create(params)
+          self.create(where)
             .success(function (instance) {
               emitter.emit('success', instance, true)
             })