Removed duplicate 'powered by Disqus' link.

This also fixes an issue during page load with Disqus comments on them, `comments powered by Disqus` displayed then got pushed down.

Author: BryceMehring

_includes/_disqus_comments.html

@@ -19,5 +19,4 @@
     }());
 </script>
 <noscript>Please enable JavaScript to view the <a href="http://disqus.com/?ref_noscript">comments powered by Disqus.</a></noscript>
-<a href="http://disqus.com" class="dsq-brlink">comments powered by <span class="logo-disqus">Disqus</span></a>
-{% endif %}
+{% endif %}