title: AuthorizeAttribute works for MVC Controller but doesn't for ApiController
body: <p>I'm relatively new to MVC and WebAPI, so perhaps I'm doing some stupid thinks. </p>
  
  <p>I'm starting my MVC + WebAPI project. I have just configured authentication, but faced a problem: [Authorize] attribute works correctly for MVC controllers and does not for API (returns always 401 error).</p>
  
  <p>I need some special configurations for API? I'm using default ApplicationSignInManager (I mean one from startup project tempalte).</p>
  
  <p>I have removed my Authorize attribute and I can see that in actions of MVC contoller User.Identity contains my signed in user, but API controller doens know nothing about it.</p>