first pass at sending email from captain, reply to captain
remove .env, use secrets.yml for development keys that don't matter
don't deliver notifications in batches. simpler to just do each individually
use notifications address for sending email
change bootstrap flash to hash, because why not?
slightly better notifications API
switch practice mailers to be from captain, to each member
switch invite mailers to be from captain, reply-to captain
switch match lineup mailers to be from captain, to each member
do not send notifications to the person sending the email