/// In most cases this will return "/" but if the site is hosted in a virtual directory then this will return the virtual directory's path such as "/mysite".
/// This value must begin with a "/" and cannot end with "/".
/// Maps a virtual path to the application's web root
/// </summary>
/// <param name="virtualPath">The virtual path. Must start with either ~/ or / else an exception is thrown.</param>
/// <returns></returns>
/// <remarks>
/// This maps the virtual path syntax to the web root. For example when hosting in a virtual directory called "site" and the value "~/pages/test" is passed in, it will