[MariaDB Packagers] MariaDB 5.5.57 release prep

Prep work for the MariaDB 5.5.57 release has begun. Expected release date will be 18 July 2017. Draft release notes and changelog: - https://mariadb.com/kb/en/mariadb-5557-release-notes/ - https://mariadb.com/kb/en/mariadb-5557-changelog/ As usual, the release notes and changelog are still being worked on and will be updated prior to release. Thanks. -- Daniel Bartholomew, MariaDB Release Manager MariaDB | http://mariadb.com