Show help by default when no arguments provided

[tanmayrajani]

Closes #20

[danburzo]

Looks good! Can we do something similar for when no command is invoked? I find myself doing percollate --output ... instead of percollate pdf --output .... Or maybe we run pdf by default when no other command is invoked?

[danburzo]

Also, we've started splitting the CLI into a separate cli.js file; sorry for breaking your PR :-) Can you put it in cli.js instead?

[tanmayrajani]

Yes, fortunately, I was watching the repo and knew those changes! :)

[tanmayrajani]

There seems to be some issues with the default command in commander but I've figured that the changes I ended up with in above commit works just right. Let me know your opinion/suggestions

[danburzo]

Let's merge it as-is for now. It would be great to raise an issue with commander.js to get a second opinion on how to best achieve this.

[danburzo]

Thank you for the contribution!