Disqus support

Added easy support for Disqus comments just add Disqus shortname to
globals and replace false with true.

This required creation of the postwrapper that also wraps posts in post
specific class and adds the post title using the _data file.

Simpler structure than seperate layouts.
Polished Disqus integration. Fixed a couple of typos. Moved aside, comments and footer content to their own partials to keep main directory cleaner. Updated README file with Disqus instructions.