OAuth: Expose the result of the token request to the notification

[Tratcher]

When the code is exchanged for a token there may be additional data returned from the provider. Expose the whole TokenResponse in the GetUserInformationAsync/Authenticated notifications.

Example: Google OpenId -> Oauth2 migrations
https://katanaproject.codeplex.com/workitem/359
https://katanaproject.codeplex.com/SourceControl/network/forks/suhasj/Katana/contribution/7719

[kevinchalet]

Ah yeah, it sucks, we forgot to expose the TokenResponse in OAuthGetUserInformationContext and OAuthAuthenticatedContext... 😄

[Eilon]

@HaoK please work with @PinpointTownes on his PR so we can try to get it in by end of next week.

[HaoK]

Merged 9bb8b61