use https when retrieving assets from CDN

lib/views/layout/layout.html

@@ -23,7 +23,7 @@
   <link rel="icon" type="image/png" href="/android-chrome-192x192.png" sizes="192x192">
 
   <!-- jQuery -->
-  <script src="//cdn.jsdelivr.net/jquery/3.2.1/jquery.min.js"></script>
+  <script src="https://cdn.jsdelivr.net/jquery/3.2.1/jquery.min.js"></script>
 
   {% if env === 'development' %}
     <script src="/dll/vendor.dll.js"></script>
@@ -41,9 +41,9 @@
   <script src="{{ webpack_asset('app').js }}" defer></script>
 
   <!-- Google Fonts -->
-  <link href='//fonts.googleapis.com/css?family=Lato:400,700' rel='stylesheet' type='text/css'>
+  <link href='https://fonts.googleapis.com/css?family=Lato:400,700' rel='stylesheet' type='text/css'>
   <!-- Font Awesome -->
-  <link href='//cdn.jsdelivr.net/fontawesome/4.7.0/css/font-awesome.min.css' rel='stylesheet' type='text/css'>
+  <link href='https://cdn.jsdelivr.net/fontawesome/4.7.0/css/font-awesome.min.css' rel='stylesheet' type='text/css'>
 
   {% block html_additional_headers %}{% endblock %}