Added RFC for Relative URL
Added common variables $scheme, $host, $path and $uri
Prevent clickjacking
Improved: hide the outline, Flexbox outdated syntax removable at Firefox 20
Fixed assets, added NETWORK: for ga.js
Improved performance on loading JavaScript's asynchronously

Improved performance:
* Increased PageSpeed Score from 92 to 95 by fixing issue on loading
ga.js asynchronously
https://plus.google.com/u/0/b/111710573164225089703/111710573164225089703/posts/7FxsrMDWMba
* Added async attribute to bottom <script> elements forwarding to
https://plus.google.com/u/0/110977198681221304891/posts/F5y1EoKJQu9

Used common variable  $uri for og:url
Added Chrome Application Cache manifest .appcache issue URL
Commented in server-side GA comment