title: Clearing backstack in NavigationService
body: <p>I am navigating through different pages within my application. After I login, I come to home page from where the navigation starts. During navigation, when I come to homepage, I want to go to the login page by pressing BackKey but I can only navigate to previously navigated page. I could have overriden the BackKeyPress event to navigate to the Login Page but in LoginPage I should again override the Backkeypress otherwise there appears to be cycle between loginpage and homepage on backkey press. Is there anyway to clear the navigation history?</p>