Redirects for Docs


The idea is to redirect these type of links:

 - `core/Module/File`
 - `core/docs/Module/File`

The idea with this part under is to allow links from "popular pages" in the docs index to be linked to that popular page in the version they were clicked, thus `req.headers.referer`

    var reqVersion = req.headers.referer && req.headers.referer.match(/(\d.\d.\d)/);
    var version = reqVersion ? reqVersion[1] : versions[0];