@using Microsoft.AspNet.Identity
@if (Request.IsAuthenticated)
{
    <ul class="nav navbar-nav navbar-right">
        <li>@Html.ActionLink("Wyloguj się", "Logout", "Login", routeValues: null, htmlAttributes: new { id = "loginLink" })</li>
    </ul>
}
else
{
    <ul class="nav navbar-nav navbar-right">
        <li>@Html.ActionLink("Zaloguj się", "Login", "Login", routeValues: null, htmlAttributes: new { id = "loginLink" })</li>
    </ul>
}