add the new-distributions game
add the new distribution game to the site
add weekly new-distributions contest
use our BackPAN::Index object, do not create a new one each time
add an accessor to obtain our BackPAN::Index directly if needed
prefetch dist to speed up the call to $release->dist
factor out the identical parts of update_author_bins

each class must define compute_author_bins to return the author bins
and the date of the latest considered release

update_author_bins is now part of the base class
Merge branch 'book/board/once-a/new-distributions'
add some space around the boards