Add switchElementsAlt() to the default switches

Fixes #83.

lib/proto/parse-options.js

@@ -1,5 +1,7 @@
 /* global _gaq: true, ga: true */
 
+var defaultSwitches = require("../switches")
+
 module.exports = function(options){
   this.options = options
   this.options.elements = this.options.elements || "a[href], form[action]"
@@ -27,10 +29,10 @@ module.exports = function(options){
   // if you set head.outerHTML, a new body tag is appended, so the dom get 2 body
   // & it break the switchFallback which replace head & body
   if (!this.options.switches.head) {
-    this.options.switches.head = this.switchElementsAlt
+    this.options.switches.head = defaultSwitches.switchElementsAlt
   }
   if (!this.options.switches.body) {
-    this.options.switches.body = this.switchElementsAlt
+    this.options.switches.body = defaultSwitches.switchElementsAlt
   }
   if (typeof options.analytics !== "function") {
     options.analytics = function() {}