When product was marked as deleted, his promotions should be deleted.
moved TODO into readme
rewrote sql - had problem with interaction of nested scopes
(is this a scopes bug?? - it ignored my later :select request...)
change to use products (not variants) as the unit of best-seller coun…
updated the docs
mysql is fussy about space between fn and args!
extended best_sellers to take a date range as args
defaults to start one week ago, finish now
added best-sellers method
returns N best sellers from the past week
first version of code
added brief info