OPENAM-2526 (CR-1799) OAuth2 Resource Owner Password Credentials Grant flow token requests fail with 500 status code. Resolved by updating the OAuthAdapter to more closely handle the OAuth tokens provided by OpenDJTokenRepo.

git-svn-id: https://svn.forgerock.org/openam/trunk/openam@5485 0f4defcf-c51a-4c67-9f44-6fb5eba73c5d