title: How to realize WebApi method that returns session id?
body: <p>I would like to realize an authentification server with ASP.NET Identity for an mobile app.
  But I don't want to use default authentification methods.
  I would like to implement an WebApi method which creates session for user by login and password and returns the session id. So, in the mobile app I will add as an json parameter this session id for each request to the server.</p>
  
  <p>Please give me an example how can I implement it? 
  I have read this article <a href="http://bitoftech.net/2014/06/01/token-based-authentication-asp-net-web-api-2-owin-asp-net-identity/" rel="nofollow">http://bitoftech.net/2014/06/01/token-based-authentication-asp-net-web-api-2-owin-asp-net-identity/</a>, but I also need an WebApi method to destroy the session, that is not possible as it described there. </p>