Updates, xx links, templates

I updated this to use the newest version of Klein, add xx links (1xx shows all of the 1xx status codes and descriptions), and templated the headers. 

On the index page, the 1xx, 2xx, etc. now are links to the xx pages. On the xx pages, the names are links to the individual page. The xx pages do not contain the code references. 

The pages have been split to use templates, so there's only a single header, which can be changed easily. 

Everything has been tested on my local system. 

I have **not** updated the .min.css.