Merge pull request #22198 from owncloud/birthday-calendar

apps/dav/appinfo/application.php

apps/dav/appinfo/register_command.php

apps/dav/command/createaddressbook.php

apps/dav/command/syncbirthdaycalendar.php

apps/dav/command/syncsystemaddressbook.php

apps/dav/lib/caldav/birthdayservice.php

apps/dav/lib/caldav/caldavbackend.php

apps/dav/lib/caldav/calendar.php

apps/dav/lib/carddav/carddavbackend.php

apps/dav/lib/rootcollection.php

apps/dav/tests/travis/caldav/script.sh

apps/dav/tests/unit/caldav/calendartest.php

apps/dav/tests/unit/carddav/birthdayservicetest.php

apps/dav/tests/unit/carddav/carddavbackendtest.php