issue 451 - MakeDrive auth should be pluggable, configurable, optional

passport-single-user? or passport-env? or passport-dev?  Don't call it json, unless you want to change it to allow the user to specify a JSON file to be loaded which looks like this:
```json
{
  "username": "password",
  "dave": "secret",
  ..
}
```

Then you could call this -json.