Removed query string for AJAX crawling rewrite

The rule no more used since Ajax SEO v3
Markup
JSON removed from humans.txt
Improved accessibility, CSP header, CSS, JavaScript

Updated CSP header
Improved small screen navigation accessibility
string() moved to config.php
Updated CSS and JavaScript
toggle() moved to window.toggle function
Improved nav, form, image accessibility

Improved form element styling
Added text-rendering: optimizeSpeed;
Unquote font-family http://mothereff.in/font-family
Chrome Android avoids scroll on touch
Image scale rendering
http://dev.w3.org/csswg/css-images/#the-image-rendering
Removed media query max-width: 1280px;
Improved navigation UX, accessibility