adding source. initial commit

source/_includes/post/author.html

@@ -0,0 +1,8 @@
+{% if post.author %}
+  {% assign author = post.author %}
+{% elsif page.author %}
+  {% assign author = page.author %}
+{% else %}
+  {% assign author = site.author %}
+{% endif %}
+{% if author %}<span class="byline author vcard">Posted by <span class="fn">{{ author }}</span></span>{% endif %}