Add status code 308

[dserodio]

From https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/308:

The HyperText Transfer Protocol (HTTP) 308 Permanent Redirect redirect status response code indicates that the resource requested has been definitively moved to the URL given by the Location headers. A browser redirects to this page and search engines update their links to the resource (in 'SEO-speak', it is said that the 'link-juice' is sent to the new URL).

The request method and the body will not be altered, whereas 301 may incorrectly sometimes be changed to a GET method.