Add users management UI

- remove the “add a user” from the config page
- add a CRUD on user
- fix some missing translations (+ bad indentation)

src/Wallabag/CoreBundle/Resources/views/base.html.twig

@@ -43,7 +43,7 @@
             {% block scripts %}
             {% endblock %}
 
-            <title>wallabag - {% block title %}{% endblock %}</title>
+            <title>{% block title %}{% endblock %} – wallabag</title>
         {% endblock %}
     </head>