merge master into filesystem

CONTRIBUTING.md

apps/files/ajax/move.php

apps/files/ajax/rename.php

apps/files/appinfo/remote.php

apps/files/css/files.css

apps/files/js/filelist.js

apps/files/js/files.js

apps/files/l10n/bg_BG.php

apps/files/l10n/bn_BD.php

apps/files/l10n/ca.php

apps/files/l10n/cs_CZ.php

apps/files/l10n/da.php

apps/files/l10n/de.php

apps/files/l10n/de_DE.php

apps/files/l10n/el.php

apps/files/l10n/eo.php

apps/files/l10n/es.php

apps/files/l10n/es_AR.php

apps/files/l10n/et_EE.php

apps/files/l10n/eu.php