Use 127.0.0.1 for fish config.

Before this change, fish config used 0 as its address. However, this
isn't a good idea from security point of view, as web service can be
accessed from everywhere, and do anything on the account it was ran on.

This also deals with firewalls which block the access to 0 even from
the host machine itself. It possibly might fix #673, but I'm not sure.