This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
I don't think that extending JspServlet is a common practice. The JspServlet class is used for the servlets that are generated from JSPs. The reason you are getting that error might be because it is looking for a class that extends HttpServlet and it can't find one. Is there any reason why you want to use JspServlet instead of HttpServlet? Also, check to make sure your ReportDownloadServlet class is the "download" package, as this is how it is defined in the deployment descriptor.