Add a hash based on the image timestamp to ensure images are reloaded whenever they are changed

AddTimeStampToImages.cs

[InitializableModule]
[ModuleDependency(typeof (EPiServer.Web.InitializationModule))]
public class AddTimeStampToImages : IInitializableModule
{
    public void Initialize(InitializationEngine context)
    {
        ContentRoute.CreatedVirtualPath += CreatedVirtualPath;
    }

    private void CreatedVirtualPath(object sender, UrlBuilderEventArgs urlBuilderEventArgs)
    {
        object contentReferenceObject;
        if (!urlBuilderEventArgs.RouteValues.TryGetValue(RoutingConstants.NodeKey, out contentReferenceObject))
        {
            return;
        }

        var routedContentLink = contentReferenceObject as ContentReference;
        if (ContentReference.IsNullOrEmpty(routedContentLink))
        {
            return;
        }

        // Check that the link is to a image
        var contentLoader = ServiceLocator.Current.GetInstance<IContentLoader>();
        var imageData = contentLoader.Get<IContent>(routedContentLink) as ImageData;
        if (imageData == null)
        {
            return;
        }

        // Check that everyone has read access to the image
        var securable = imageData as ISecurable;
        if ((securable.GetSecurityDescriptor().GetAccessLevel(PrincipalInfo.AnonymousPrincipal) & AccessLevel.Read) !=
            AccessLevel.Read)
        {
            return;
        }

        // Generate timestamp
        var hash = imageData.Saved.Ticks.ToString("X").Substring(2, 8).ToLower();

        // Generate new url with a querystring
        if (urlBuilderEventArgs.UrlBuilder.Query == string.Empty)
        {
            urlBuilderEventArgs.UrlBuilder.Path += "?hash=" + hash;
        }
        else
        {
            urlBuilderEventArgs.UrlBuilder.Path += "&hash=" + hash;
        }
    }

    public void Preload(string[] parameters)
    {
    }

    public void Uninitialize(InitializationEngine context)
    {
        ContentRoute.CreatedVirtualPath -= CreatedVirtualPath;
    }
}