Add visibility to all constants

apps/comments/lib/AppInfo/Application.php

apps/dav/lib/AppInfo/Application.php

apps/dav/lib/CalDAV/Activity/Provider/Calendar.php

apps/dav/lib/CalDAV/Activity/Provider/Event.php

apps/dav/lib/CalDAV/BirthdayCalendar/EnablePlugin.php

apps/dav/lib/CalDAV/BirthdayService.php

apps/dav/lib/CalDAV/CalDavBackend.php

apps/dav/lib/CalDAV/Plugin.php

apps/dav/lib/CalDAV/Proxy/ProxyMapper.php

apps/dav/lib/CalDAV/Publishing/PublishPlugin.php

apps/dav/lib/CalDAV/Schedule/IMipPlugin.php

apps/dav/lib/CalDAV/Search/SearchPlugin.php

apps/dav/lib/CalDAV/WebcalCaching/Plugin.php

apps/dav/lib/CardDAV/CardDavBackend.php

apps/dav/lib/CardDAV/Xml/Groups.php

apps/dav/lib/Command/MoveCalendar.php

apps/dav/lib/Comments/CommentNode.php

apps/dav/lib/Comments/CommentsPlugin.php

apps/dav/lib/Comments/EntityCollection.php

apps/dav/lib/Connector/Sabre/Auth.php