per @epriestley:
> Possible Use Case: Alternate Short Domain
>
> We could let users configure a short domain which pipes directly into Phurl. For example, an install might be hosted at `phabricator.mycompany.com`, but a shorter domain like `mcmp.me` is configured as the Phurl domain. Phurl then recognizes requests on this domain, and emits URLs using this domain (`https://mcmp.me/2`). The old URLs still work correctly.