Remove can_modify context variable, use is_staff instead

For both ban and modify actions, we trust staff users to not abuse
otherwise-secret scripts and links. We don't supply "can_modify" context
variable anymore and just use user.is_staff instead. The same goes for
ban links and scripts.

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

board/templates/board/base.html

@@ -12,10 +12,8 @@
         <script src="{% static 'board/jquery.js' %}"></script>
         <script src="{% static 'board/jsframe.min.js' %}"></script>
         <script src="{% static 'board/post.js' %}"></script>
-        {% if perms.board.add_ban %}
+        {% if user.is_staff %}
             <script src="{% static 'board/ban.js' %}"></script>
-        {% endif %}
-        {% if can_modify %}
             <script src="{% static 'board/modify.js' %}"></script>
         {% endif %}
         {% block extrajs %}{% endblock %}