Create and/or document database backup strategy

[brittag]

Description

Questions that occurred to me related to a bug that accidentally removed a few keycode assignments (https://github.com/doubleunion/arooo/pull/730):

Do we have our Heroku resources set up to backup our member-info database on a regular basis and retain the backups for some reasonable amount of time? Have we tested restoring from backup? Let's document this in our readme as well.