Fix #3624, separate out 19.1.0 and 19.2.0 in changelog
Fix #3624, separate out 19.1.0 and 19.2.0 in changelog

This includes all the latest commits (under no version) so that they won't get lost the next time ./bin/generate-commit-log recent is called

mozilla-services/screenshots,mozilla-services/screenshots,mozilla-services/pageshot,mozilla-services/screenshots,mozilla-services/pageshot,mozilla-services/screenshots,mozilla-services/pageshot,mozilla-services/pageshot