don't send referrer headers on pads which may link outward

www/code/index.html

@@ -5,6 +5,7 @@
     <meta content="text/html; charset=utf-8" http-equiv="content-type"/>
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
     <link rel="stylesheet" href="/bower_components/components-font-awesome/css/font-awesome.min.css">
+    <meta name="referrer" content="no-referrer" />
     <script data-bootload="main.js" data-main="/common/boot.js" src="/bower_components/requirejs/require.js"></script>
     <link rel="icon" type="image/png"
         href="/customize/main-favicon.png"

www/pad/index.html

@@ -4,6 +4,7 @@
     <title>CryptPad</title>
     <meta content="text/html; charset=utf-8" http-equiv="content-type"/>
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <meta name="referrer" content="no-referrer" />
     <link rel="stylesheet" href="/bower_components/components-font-awesome/css/font-awesome.min.css">
     <script data-bootload="main.js" data-main="/common/boot.js" src="/bower_components/requirejs/require.js"></script>
     <link rel="icon" type="image/png"

www/slide/index.html

@@ -4,6 +4,7 @@
     <title>CryptPad</title>
     <meta content="text/html; charset=utf-8" http-equiv="content-type"/>
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <meta name="referrer" content="no-referrer" />
     <script data-bootload="main.js" data-main="/common/boot.js" src="/bower_components/requirejs/require.js"></script>
     <link rel="icon" type="image/png"
         href="/customize/main-favicon.png"