Include a site show page

This is a page which can display the details about a site, rather than
cluttering up the Mappings page. It will possibly become a dashboard for the
transition of that site.
Move site details link to its own column

* Remove the homepage column
* Add a site details column at the far right (avoid linking the site
domain as that could cause confusion)
Clean up site details page

* Spread out the definition list now we have more space
* Use longer definition titles
* Remove mapping and analytics titles from header and add below

We should consider adding help text to explain the more complicated
properties on this page.
Update site details title
Reposition analytics and mappings in list

Because of the likelihood of landing on this page from a breadcrumb the
mappings and analytics links should be further up to help with
switching between the two.
Merge pull request #127 from alphagov/site_show_page

Include a site show page