New redis keys are partitioned per service per day. New process is as
follows:
* require a count of days to filter by. Currently admin always gives 7.
* for each day, check and see if there's anything in redis. There won't
be if either a) redis is/was down or b) the service didn't send any
notifications that day
- if there isn't, go to the database and get a count out.
* combine all these stats together
* get the names/template types etc out of the DB at the end.
it's used in a few places - it should definitely know what timezones
are and return datetimes rather than dates, which are hard to work with
in terms of figuring out how tz aware they are.
