Generic transport editor. (#1309)

Generic transport editor.

see #1301

* Fixed unit test.

* Added unit tests.

* Fixed unit test.

* Added transport module to test list.

* Moved relay transport backend to appropriate app.

see #1301

* Added missing file.

modoboa/templates/twocols.html

@@ -3,11 +3,14 @@
 {% load core_tags %}
 
 {% block container_content %}
-<div id="leftcol" class="sidebar collapse navbar-collapse">
-  {% block leftcol %}{% endblock %}
-</div>
-<div class="main">
-  {% if messages %}{% display_messages messages %}{% endif %}
-  {% block apparea %}{% endblock %}
-</div>
+  <div id="leftcol" class="sidebar collapse navbar-collapse">
+    {% block leftcol %}{% endblock %}
+  </div>
+  <div class="main">
+    {% block apparea %}{% endblock %}
+  </div>
+{% endblock %}
+
+{% block extra_js %}
+  {% if messages %}{% display_messages messages %}{% endif %}
 {% endblock %}