Namely start conforming with POSIX for the usage line and make user.follow, user.unfollow work properly.
This makes gh-cli depends setuptools (or distribute). But it's not a real problem because gh-cli already uses `entry_point` to create script.
This should be the end of the gist work. [ci skip]
Everything is still broken though. [ci skip]
I'm redesigning YET AGAIN [ci skip]
And you can now fork a gist as well. :)