fix(config): Auto-detection of site root
fix(config): Auto-detection of site root

In #308, we tried to auto-detect the site root.  Unfortunately, the
fallback for when it wasn't found overwrote the auto-detected location
and a test wasn't fully implemented to catch this.

cobalt-org/cobalt.rs,cobalt-org/cobalt.rs,cobalt-org/cobalt.rs,cobalt-org/cobalt.rs