Squashed 'libertree-backend-rb/' changes from d977aa0..ece3061

ece3061 add default config.yaml with keys that need to be customised
ae6d5ba Added :openssl_verify_mode to SMTP config.

git-subtree-dir: libertree-backend-rb
git-subtree-split: ece3061f3585e1f39e8ec3b20e9964728fd0f517
Merge commit '56d8079b0dabcab0573366d7b4af6eef4f8bf173'