added login and logout api calls

I've added other two methods to solution and commited to github.
I've started simple solution by implementing in standard Mvc way to
write api.
Since you have stated in project title that you want WebAPI version of
api, I've added it to solution (side-by-side).

You can choose whichever implementation flavor you like better.
1. Standard Mvc (UserController.cs + RouteConfig.cs) -
/api/v5/user/{action}
2. WebAPI (User1Controller.cs + WebApiConfig.cs) -
/api1/v5/user1/{action}

To switch Api implementations calls in test page simply change
(uncomment) the ajax url route on Index.cshtml lines: 88/89
I've added very simple user repository for testing purposes.