For #242, move the updating of the POTD sequence into a new signals module. When photos are deleted from the admin changelist in bulk, the individual delete() functions on the photo objects is not called. However, the post_delete signal is called for each object.

{% load core_tags %}
<p>
<span class="shoutbox-user">{{ shout.user.username }}:</span>
<span class="shoutbox-shout">{{ shout.html|safe }}</span><br />
<span class="shoutbox-date">{{ shout.shout_date|elapsed }}</span>
</p>