The shell isn't visible, so it doesn't need these remnants from
Terminal.

`process` only exists when running in Node. Notably, `if (process)` is
still a ReferenceError, so the existing checks need modifying too.

Previously we were reading `config.source` and then removing the
trailing slash. However, this doesn't include the port, which we use
when running locally. `config['puter.api_origin']` is actually what we
want, which does have the port if it's set, and doesn't include the
trailing slash either.