nut publish without arguments should publish a nut in current directory

[AlekSi]

Only if there is strictly one.

(AlekSi/gonuts.io#19)

[yvasiyarov]

It will be very nice.
Or at least add some error message if no arguments is passed.
Because I run "nut publish" (with verbose = true!) and its just exit without any error message

I was though what my nut is published and it take some time to understand what I have to pack it first.
Even if you run "nut help publish" its not clean at all - what is "test_nut1-0.0.1.nut" and how you can create it