remove fetch api - we don't want no polyfills, and already have jQuery

frontend/src/Metamaps/Mapper.js

@@ -1,17 +1,19 @@
+/* global $ */
+
 /*
- * Metamaps.Backbone
+ * Dependencies:
+ *  Metamaps.Backbone
  */
 
 const Mapper = {
   // this function is to retrieve a mapper JSON object from the database
   // @param id = the id of the mapper to retrieve
   get: function (id, callback) {
-    return fetch(`/users/${id}.json`, {
-    }).then(response => {
-      if (!response.ok) throw response
-      return response.json()
-    }).then(payload => {
-      callback(new Metamaps.Backbone.Mapper(payload))
+    $.ajax({
+      url: `/users/${id}.json`,
+      success: data => {
+        callback(new Metamaps.Backbone.Mapper(data))
+      }
     })
   }
 }