apocas/docker-modem — pull request #26 by refractalize (2014-07-23 18:22:43+00:00)
Title: X-Registry-Auth should be now JSON and Base64

I'm assuming that `cfg.authconfig` is a JSON object of the form:

{
username: "bob",
password: "password123",
email: "bob@example.com"
}

If that's the case we need to stringify and base64 encode it.