HTML cleanup

Some fixes for the views you see in a browser when Manage is not installed.

* Remove the colon in the copyright notice in the footer
* Link to absolute URLs for the CSS so it actually works
* Link to local images in the CSS, instead of opscode.com hosted ones
* Remove link to https://manage.opscode.com
* Make the main text wrap if it's at less than 940px

Note that because of how the Lua config stuff is set up, going to /foo/bar will not go to a 404 page, but render the index page as a 200. But, going to /images/foo or /css/foo will render the 404 page. This PR doesn't change that, but it does make it so the 404 pages load the CSS and images correctly.