We referred to this locally generated UUID as "API token" which was wrong,
because it doesn't have any special API powers, and is only used to link local
machine with uploaded recordings, so they can later be associated with
asciinema.org account.
It's more of device token or installation ID in nature, so let's call it
"install ID" for short, and keep it at ~/.config/asciinema/install-id.
Keeping it in automatically created config file also turned out to be not the
best idea - the config was mixing user preferences with local, device specific
state, preventing easy publishing of the config (for example in a public
dotfiles repository).
