fix(config): only show config location once

this fixes a bug that has been introduced in a previous PR that shows 'reading config from...' multiple times during startup.

the culprit for the fix is https://github.com/hoodiehq/hoodie-server/commit/f9e72aacc0cf0d42c149eb586f0e2c1c4663ef01

/cc @caolan @gr2m @janl @boennemann