Add a "sign in" button to the menu bar when the user is not signed in.

This will hopefully make it more noticeable when one got logged out.

Commit ready for merge.
 - Legacy-Id: 19467

ietf/templates/base.html

@@ -74,6 +74,12 @@
 	    <ul class="hidden-nojs nav navbar-nav">
               {% include "base/menu.html" with flavor="top" %}
             </ul>
+        {% if not user.is_authenticated %}
+            <p class="navbar-text"></p>
+            <button type="button" class="btn {% if server_mode and server_mode == "production" %}btn-warning{% else %}btn-default{% endif %} btn-sm navbar-btn">
+                <a style="color:inherit" rel="nofollow" href="/accounts/login/?next={{request.get_full_path|urlencode}}">Sign in</a>
+            </button>
+        {% endif %}
 
 	    <form class="navbar-form navbar-right hidden-xs" action="/doc/search/">
 	      <div class="form-group">
@@ -177,5 +183,4 @@
 	 <script src="{% static 'jquery.tablesorter/js/jquery.tablesorter.combined.min.js' %}"></script>
       {% endif %}
   </body>
-</html>
-
+</html>