[MariaDB Packagers] MariaDB 5.5.60 release prep

Prep work for the MariaDB 5.5.60 release has begun. Expected release date is Mon 23 Apr 2018. Draft release notes and changelog: - https://mariadb.com/kb/en/mariadb-5560-release-notes/ - https://mariadb.com/kb/en/mariadb-5560-changelog/ As usual, the release notes and changelog are still in draft form at this time and will be updated prior to release. Thanks. -- Daniel Bartholomew, MariaDB Release Manager MariaDB | http://mariadb.com