[Feature] Staticman v3 Support (#440)

* Added Staicman support

* Corrected template for staticman.yml

* Edit for coherence with _includes/disqus.html

* Updated documentation for Staticman

* Updated License to give credits to Michale Rose

* Update LICENSE

* add more staticman details to readme

* Clearer instructions about reCAPTCHA in YML

* Nest reCAPTCHA param inside Staticman

* Prepend all css selectors with .staticman-comments

Edit suggested by theme owner to avoid CSS rules overriding.

* Add myself to the change log

* Update _config.yml

_layouts/post.html

@@ -70,6 +70,9 @@ layout: base
           {% include disqus.html %}
         </div>
           {% include fb-comment.html %}
+        <div class="staticman-comments">
+          {% include staticman-comments.html %}
+        </div>
       {% endif %}
     </div>
   </div>