Verify external providers are using latest APIs

[Tratcher]

RTM milestone.

External login providers routinely update their APIs and deprecate the old ones. Before we ship RTM we need to verify that each of our implementations is targeting the latest provider API versions to ensure our packages have the longest useful lifespan.

Example: #85

[brentschmaltz]

What is the definition for an 'External login provider'?

[Praburaj]

Like Google, Facebook, Twitter, MicrosoftAccount etc.

[Tratcher]

FYI: Facebook is up to v2.4: https://developers.facebook.com/blog/post/2015/07/08/graph-api-v2.4/
https://katanaproject.codeplex.com/workitem/417
aspnet/Security#365

[muratg]

Let's have a look in RC2.

[Tratcher]

MSA: aspnet/Security#691

[HaoK]

Google Token Endpoint to v4: aspnet/Security#829

[HaoK]

FB to v2.6 aspnet/Security#828