suggested change to callback format

[npomfret]

@jamiltz I'd like to change the native code to no longer return a url with the username and password embedded in it. It just feels a bit funky and forces the javascript to do some unnecessary parsing. Instead of returning a string url, i'd like to change both implementations to return something like this:

{
  host: "localhost",
  port: 8484,
  username: "username",
  password: "password"
}

... then we can pass these parameters around more explicitly.

Or, (maybe more secure than this) instead of passing the username and password for the local db, we just pass an encoded auth token? Putting the username and password in clear text in the url doesn't feel as good as setting the encoded auth header.