Arquivo404 Should point towards the oldest version of a website

[VascoRatoFCCN]

Arquivo404 currently defaults to loading the most recent version available on Arquivo.pt . This shouldn't be the case for several reasons:

• Often when a website is faced with a 404, it simply redirects the user to the main page, and sometimes the most recent version of a page in Arquivo.pt reflects this behavior. (ex: This Arquivo404 link)
• An archive is more valuable the older its preserved contents are, we should give emphasis to the more valuable content and not the more easily available one.
• From our own experience, users usually are looking for the older versions of websites, as such this change would improve user experience.

[dcgomes]

Test again after milestone Francisco.

[VascoRatoFCCN]

Fixed in arquivo/arquivo404@01801dd