Fixed on documentation.

* replaced previously removed concepts/containers and concepts/introcution by a redirect
* moved orphan index/varable to workingwiththerepository
* added favicon to the layout.html
* added redirect_home which is a http refresh redirect. It works like a 301 for google
* fixed an issue in the layout that would make it break when on small screens
Merge pull request #921 from dhrp/docs-redirects-and-fixes

Fixes on documentation. LGTM