Implements DISQUS support

[tkovs]

I'm using this theme on my blog and I wish it had Disqus support.

[tkovs]

@gayanvirajith check this

[taher435]

@tkovs - I would like to recommend a small change. It will be great to have a post level setting to enable or disable comments. If I am writing a certain article where I don't want participation, I can just set the flag on the post to false. Something like this,

{% if site.harmony.disqus_shortname and page.comments == true %}
      <div class="comments">
          {% include disqus.html %}
      </div>
{% endif %}

[tkovs]

omg! this... I'll check this soon and do it in my fork 'cause I gonna improve the template to use on my blog.