Keama should be more verbose

Right now keama is completely silent in positive case. It would be useful to write something to stdout when the conversion happens. Something like:

• "Reading input file xyz.conf"
• "Subnet 123.45.67.89/24 converted"
• "Hostname 11:22:33:44:55:66 converted"
• "Written output to xyz.json"

This would be useful for users to know how the conversion went. When implementing the web interface, I've tried to capture stdout and stderr from keama, but couldn't make it print anything useful on stdout.