Allow "bin/auth recover" to succeed before phabricator.base-uri is set

Summary:
Fixes T4132. If you run "bin/auth recover" before setting the base URI, it throws when trying to generate a production URI.

Instead, just show the path. We can't figure out the domain, and I think this is less confusing than showing "your.phabricator.example.com", etc.

Test Plan: Ran `bin/auth recover <user>` for valid and missing base-uri.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T4132

Differential Revision: https://secure.phabricator.com/D7615