Merge branch 'develop' of git.ispconfig.org:ispconfig/ispconfig3 into develop

install/lib/installer_base.lib.php

install/tpl/apache_acme.conf.master

install/tpl/apache_ispconfig.conf.master

interface/web/dashboard/dashlets/databasequota.php

interface/web/dashboard/dashlets/quota.php

server/conf/apache_ispconfig.conf.master

server/lib/classes/cron.d/100-monitor_database_size.inc.php

server/lib/classes/cron.d/100-monitor_hd_quota.inc.php

server/lib/classes/monitor_tools.inc.php

server/plugins-available/mysql_clientdb_plugin.inc.php