Discourse SSO (#560)

* Alter Discourse support to act as SSO provider.
Correct service group sync retry queueing.

* Correct default database enviroment variable names.

* Redirect to requested page after succesful login.

* Correct default redirect handling.
Correct attribute used to logout users on Discourse.
Improve logging messages to use parsed path on Discourse.

* Correct task retry syntax using bind=True.
Inherit from base exception so can catch TeamspeakErrors.

stock/templates/public/login.html

@@ -60,6 +60,7 @@
                     {% csrf_token %}
                     <h2 class="form-signin-heading text-center">{% trans "Please sign in" %}</h2>
                     {{ form|bootstrap }}
+                    <input type="hidden" name="next" value="{{ request.GET.next }}" />
                     <div class="row">
                     <div class="col-md-12">
                         <button class="btn btn-lg btn-primary btn-block" type="submit">{% trans "Sign in" %}</button>

stock/templates/registered/services.html

@@ -238,18 +238,10 @@
             {% endif %}
             {% if SHOW_DISCOURSE %}
                 <td class="text-center">Discourse</td>
-                <td class="text-center">{{ authinfo.discourse_username }}</td>
+                <td class="text-center">{{ char.character_name }}</td>
                 <td class="text-center"><a href="{{ DISCOURSE_URL }}">{{ DISCOURSE_URL }}</a></td>
                 <td class="text-center">
-                    {% ifequal authinfo.discourse_username "" %}
-                        <a href="{% url 'auth_activate_discourse' %}" class="btn btn-warning">
-                            <span class="glyphicon glyphicon-ok"></span>
-                        </a>
-                    {% else %}
-                        <a href="{% url 'auth_deactivate_discourse' %}" class="btn btn-danger">
-                            <span class="glyphicon glyphicon-remove"></span>
-                        </a>
-                    {% endifequal %}
+                    <a class="btn btn-success" href="{{ DISCOURSE_URL }}"><span class="glyphicon glyphicon-arrow-right"></span></a>
                 </td>
             {% endif %}
             {% if SHOW_TEAMSPEAK3 %}