Do not print verbose info about app updates if there are none

This is cosmetical but if you have a large number of apps installed then
you'll see a wall of text during the server and app upgrade when it
tries to update each app via the app store. In may cases nothing will be
updated. For those boring cases we can hide the verbose info, but show
when occ is run with -v. Any actual update will still print a few lines.
Those are the important ones for the admin.

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>