ENABLE_STARTTLS is designed to replace ENABLE_STARTTLS_AUTO by accepting
three values: 'auto' (the default), 'always', and 'never'. If
ENABLE_STARTTLS isn't provided, we fall back to ENABLE_STARTTLS_AUTO. In
this way, this change should be fully backwards compatible.
Resolves#20311
* Change references to tootsuite/mastodon to mastodon/mastodon
* Remove obsolete test fixture
* Replace occurrences of tootsuite/mastodon with mastodon/mastodon in CHANGELOG
And a few other places
* Add ffmpeg buildpack for scalingo.
* Add environment variable to install ffprobe
Note: For existing applications, admins needs to add 'WITH_FFPROBE=true' to environment variable.
* Allow SMTP auth method customization
* Add SMTP openssl_verify_mode option support
Allows one use self-signed certs with their SMTP server.
* Add SMTP enable_starttls_auto option support
