1. Exeption will be still thrown from CreateTicketAsync to avoid breaking
change.
2. OAuthHandler won't try to capture the exception.
3. OAuthHandler will check if the AuthenticateTicket is null.
4. RemoteAuthenticationHandler's error handling flow is improved to cover
the exception thrown from HandleRemoteAuthenticateAsync. The exeption
thrown from it will go throw the user error handling logic, too.
1. Check the response states code. If it is out of 2XX range, compose a
readable message and throw in an exception.
2. Capture the exception in HandleRemoteAuthenticateAsync and translate
it into AuthenticateResult.
Troy Dai
Mike Surcouf
N. Taylor Mullen