JCLOUDS-633: Support passing bearer token directly for OAuth2

https://issues.apache.org/jira/browse/JCLOUDS-633
Work in progress, I will be adding some tests soon but wanted to expose this for review.
I thought it might be necessary as a default but the way the OAuthModule is used, but you are correct, the binding will always be there anyway so there is no point.  I'm removing it.