Format the instance list as a proper table
Move region switching to a command line parameter
Remove stray debug message in load_config
Allow passing a command to run on the instances
Adjust SSH options for a bit more convenient experience
Make SSH host key check disabling optional
Remove 'better formatting' from the TODO list

This was improved in commit a00c3a6f312d953485ea3db27907be4097ee14ef.
Advertise new features in the README