Merge branch 'master' into calendar_import

apps/files_versions/ajax/expireAll.php

apps/files_versions/ajax/getVersions.php

apps/files_versions/ajax/rollbackVersion.php

apps/files_versions/appinfo/app.php

apps/files_versions/history.php

apps/files_versions/lib/hooks.php

apps/files_versions/lib/versions.php

lib/filesystem.php

lib/filesystemview.php