Make Api mixin usable as a standalone module

src/mixins/api.jsx

@@ -4,8 +4,6 @@ var xhr = require('xhr');
 var jar  = require('../lib/jar.js');
 var log = require('../lib/log.js');
 
-var CookieMixinFactory = require('./cookieMixinFactory.jsx');
-
 /**
  * Component mixin that constructs requests to the scratch api.
  * Custom arguments:
@@ -15,10 +13,6 @@ var CookieMixinFactory = require('./cookieMixinFactory.jsx');
  * It also takes in other arguments specified in the xhr library spec.
  */
 var Api = {
-    mixins: [
-        // Provides useScratchcsrftoken
-        CookieMixinFactory('scratchcsrftoken', '/csrf_token/')
-    ],
     api: function (opts, callback) {
         defaults(opts, {
             host: window.env.API_HOST,
@@ -57,7 +51,7 @@ var Api = {
             opts.headers['Accept-Language'] = jar.get('scratchlanguage') + ', en;q=0.8';
         }
         if (opts.useCsrf) {
-            this.useScratchcsrftoken(function (err, csrftoken) {
+            jar.use('scratchcsrftoken', '/csrf_token/', function (err, csrftoken) {
                 if (err) return log.error('Error while retrieving CSRF token', err);
                 opts.json.csrftoken = csrftoken;
                 opts.headers['X-CSRFToken'] = csrftoken;