Blog: add permalink on partial entries.

I noticed there is no link on the blog pages (other than on the front
page) to get the link to the blog post itself.  This adds a permalink at
the end near the tags.

I considered making the title itself a link, which is what's done on the
frontpage, but I figured this might look nicer.  Feel free to change
this if you're looking this commit message and feel I didn't DTRT
here. :)

www/conservancy/templates/blog/entry_partial.html

@@ -36,6 +36,9 @@ This partial accepts these optional parameters:
 {% if show|default:"body" != "body" %}
 <p><a class="continued" href="{{ entry.get_absolute_url }}">Read More&hellip;</a></p>
 {% endif %}
+{% if show != "summary"}
+<p class="permalink"><a href="{{ entry.get_absolute_url }}">[permalink]</a></p>
+{% endif %}
 
 {% if show != "summary" and entry.tags.exists %}
 <p class="blog-tags">Tags: