Modifications to index.html

* Changed 4 spaces for indents to tabs (4 spaces width)
* Moved Modernizr js to bottom of page because it should be with the rest
* Cleaned up CSS a little, couple less breaks
* Moved H5BP css classes above the custom css because we want to allow people to override them if they wish
* Changed main section to main element to fit with HTML5 standards
* Changed {HasPages} to be inside the nav list; ask, submit and archive should show there even if there is no pages (otherwise they don't show if theres no pages)
* Standardized figcaptions cause they were annoying me ;)

+ Added {SubmissionsEnabled} & label to nav
+ added HTML5shiv and js fixer for less than IE9 browsers

- Removed note count block within text post, isn't it in the posts footer?