Fix chain to be a helper, not a method.
[misc/bug] Fixed a bug where chain did not fire onedone events for immediately ready promises.
[misc/refactor] Clean up handling AccessToken grant result
[misc/refactor] Create a Credentials type
[misc/refactor] Merge new Credentials and AccessToken. Acts now both as the credentials for resources, and also an interface to query credentials' properties.
[misc/refactor] Use Credentials to auth Database resources.
[#13] Implemented a SetSecret permission, given automatically to credentials which create others.