setup: allow setup without auth; allow to get token manually

[perlpunk]

Currently, without a ~/.git-hub config, setup will start for any command.

The setup process wants a login and password.

Especially new users may just want to try it out without doing the
full setup.

Setup process should let you choose if you want to use auth or not.

When getting the token, user should be able to choose to type in the
password or to create a token themselves (just show the link to
the personal access token page).