Readd ajax.js to webpack mix

Author: antonioalmeida

webpack.mix.js

@@ -14,6 +14,7 @@ let mix = require('laravel-mix');
 mix.sass('resources/assets/sass/app.scss', 'public/css').scripts([
     'resources/assets/js/fontawesome-all.min.js',
     'resources/assets/js/summernote.js',
+    'resources/assets/js/ajax.js',
     'resources/assets/js/script.js',
     'resources/assets/js/searchbar.js',
     'resources/assets/js/offcanvas.js',