refactor(templates): remove ddusers.user_login/logout from top-nav

use shibboleth:login/logout instead

discuss_data/templates/nav-top.html

@@ -27,11 +27,11 @@
         <ul class="navbar-nav ml-auto">
             {% if request.user.is_authenticated %}
             <li class="nav-item">
-                <a class="nav-link" href="{% url 'ddusers.user_logout' %}">{% trans "Sign Out" %}</a>
+                <a class="nav-link" href="{% url 'shibboleth:logout' %}">{% trans "Sign Out" %}</a>
             </li>
             {% else %}
             <li class="nav-item" data-toggle="modal" data-target="#signIn">
-                <a id="log-in-link" class="nav-link" href="{% url 'ddusers.user_login' %}">{% trans "Sign In" %}</a>
+                <a id="log-in-link" class="nav-link" href="{% url 'shibboleth:login' %}">{% trans "Sign In" %}</a>
             </li>
             {% endif %}
         </ul>