CPAN Ratings upgrade

I did a bit of work on CPAN Ratings today.

The RSS feeds for reviewers and distributions should work (better) now.

I added "alternate" headers for the RSS feeds so your tools can find the RSS feeds more easily.

I also implemented a proper API for the helpful votes. This was just to make it easier to make other API things in the future (and to maybe make the site support non-javascript browser some day ;-) )

If the site doesn't work properly, be sure to clear your cache, shift-reload etc etc. (The .js and .css files aren't versioned so your browser or ISP proxy might have cached the old versions).