feat(auth): move AUTH_SECRET to db

This PR moves the the AUTH_SECRET to a database config entity which removes
the requirement to have a localized version of the `authenticationSecret.cfg`.
chore(auth): updated README, removed unused config file
fix(auth): let get_auth_secret return created secret
Merge pull request #4 from dothiv/remove-AUTH_SECRET-from-config

Remove auth secret from config