Handle`KeyboardInterrupt` at a higher level

[gprossliner]

Currently we are handling KeyboardInterrupt at various places, but still get some nasty error logs from CTRL+C. We should handle that at cli.py level for all commands at once.

Code that needs explicit handling (like attach), will continue with a local handler, but all other code should just fall back to the global handler. This should print something like Operation canceled by user