Merge pull request #2 from PinpointTownes/dev

Use SystemClock, favor ExpiresUtc when present and make SigningCredentials mandatory
Update README.md
First attempt to fork the Microsoft.Owin.Security.OAuth repository
Incorporate IdToken management in the forked bits
Merge pull request #12 from PinpointTownes/experimental

Use a whole new approach based on a Katana OAuthAuthorizationServerHandler fork