This relates to issue #253. Dockerfile and docker-compose.yml have
been added to the project eliminating the need to use packer for
producing container images, but the documentation was not updated.
https://github.com/docker-library/mysql/issues/419
ERROR 2059 (HY000): Authentication plugin 'caching_sha2_password' cannot be loaded
Resolve by explicitly testing with mysql5.7 docker image... there are other ways around it but this guide is for devs to test quickly.
* Clean/refactor notifier, add user validation
Fix a few notifier bugs, move reminder/user validator to their own
files, add Makefile to docs
* Move reminder/user validator to notifier directory
