fixed petstore link

dist/swagger-ui.js

@@ -1303,7 +1303,7 @@ helpers = this.merge(helpers, Handlebars.helpers); data = data || {};
 
     HeaderView.prototype.showPetStore = function(e) {
       return this.trigger('update-swagger-ui', {
-        url: "http://petstore.swagger.wordnik.com/api/api-docs.json"
+        url: "http://petstore.swagger.wordnik.com/api/api-docs"
       });
     };
 

src/main/coffeescript/view/HeaderView.coffee

@@ -12,7 +12,7 @@ class HeaderView extends Backbone.View
   showPetStore: (e) ->
     @trigger(
       'update-swagger-ui'
-      {url:"http://petstore.swagger.wordnik.com/api/api-docs.json"}
+      {url:"http://petstore.swagger.wordnik.com/api/api-docs"}
     )
 
   showWordnikDev: (e) ->