adding a redirected to the originaly requested page on login

user not authenticated and requesting an url are redirected to
the signin page with the requested page url as the query string (in
base64). It permits to redirect them to the requested page once they
've log in.

resources/templates/login.tmpl

@@ -4,7 +4,13 @@
     <div class="row clearfix" style="margin-top:30px">
         <div class="col-md-4 column"></div>
         <div class="col-md-4 column well">
-            <form method='POST' action='/login' role="form" class="form-signin">
+<%
+if url is None:
+    qs=''
+else:
+    qs='?url=' + url
+%>
+            <form method='POST' action='/login${qs}' role="form" class="form-signin">
               <div class="form-group">
               <h2 class="form-signin-heading">Please sign in</h2>
                 <div class="input-group">