This release switches from the bitnami image to the official discourse/discourse
image. Some env vars need to be renamed for this migration; everything else
should happen automatically.

Rename these in your app's .env (the values carry over):

  DISCOURSE_SMTP_HOST     --> DISCOURSE_SMTP_ADDRESS
  DISCOURSE_SMTP_USER     --> DISCOURSE_SMTP_USER_NAME
  DISCOURSE_SMTP_AUTH     --> DISCOURSE_SMTP_AUTHENTICATION
  DISCOURSE_SMTP_PROTOCOL --> DISCOURSE_SMTP_ENABLE_START_TLS (takes a boolean true/false, not the old tls/ssl value, so translate it rather than copying it straight across)