Null Exception in System.Security.Claims

This fixed a runtime exception when trying to get a ClaimsPrincipal from an IIdentity.
Noticed this work working with aspnet Identity in a Web Api 2 controller.
Exception fired when running User.Identity.IsAuthenticated.

Exception detail:
http://falk.pw:7777/tocehuhemo.xml
Merge pull request #1078 from LRFalk01/master

Null Exception in System.Security.Claims