ros-get update should be less spammy

[alberth]

The update command (but also install, and perhaps other commands as well), is quite spammy in its output. It would be useful if it doesn't report about things that are correct already (perhaps still allowing to get the information with eg a --verbose flag).

That way, you can more easily read what gets actually changed or updated without getting lost in all the output.

Obviously, the other way around (adding a flag to reduce the amount of output) would work too.