module documentation

Cred errors.

Exception LoginDenied The realm rejected this login for some reason.
Exception LoginFailed The user's request to log in failed for some reason.
Exception Unauthorized Standard unauthorized error.
Exception UnauthorizedLogin The user was not authorized to log in.
Exception UnhandledCredentials A type of credentials were passed in with no knowledge of how to check them. This is a server configuration error - it means that a protocol was connected to a Portal without a CredentialChecker that can check all of its potential authentication strategies.