don't show a notification while keeping files available offline

At the moment we show a notification for keep available offline, e.g. whenever we "re-download" a file that has changed on the server and is marked "available offline". Since such operations are to be considered "the default behavior of what needs to happen" it vote for not displaying such a notification since as a user I expect the app to keep the file in sync and not telling me that it is doing exactly that "all the time".