Update license headers

AUTHORS

apps/dav/appinfo/app.php

apps/dav/appinfo/install.php

apps/dav/appinfo/register_command.php

apps/dav/appinfo/update.php

apps/dav/appinfo/v1/caldav.php

apps/dav/appinfo/v1/carddav.php

apps/dav/appinfo/v1/publicwebdav.php

apps/dav/appinfo/v1/webdav.php

apps/dav/lib/AppInfo/Application.php

apps/dav/lib/CalDAV/BirthdayService.php

apps/dav/lib/CalDAV/CalDavBackend.php

apps/dav/lib/CalDAV/Calendar.php

apps/dav/lib/CalDAV/CalendarHome.php

apps/dav/lib/CalDAV/CalendarRoot.php

apps/dav/lib/CardDAV/AddressBookImpl.php

apps/dav/lib/CardDAV/CardDavBackend.php

apps/dav/lib/CardDAV/SyncJob.php

apps/dav/lib/CardDAV/SyncService.php

apps/dav/lib/Command/CreateAddressBook.php