Fix Eclipse compile errors

* Most web.xml servlet API versions updated to 3.0 for ASYNC support
* httpsession-xml is left at 2.5 to ensure compatability & remove ASYNC
* Remove @Override on interface override

samples/httpsession-jdbc/src/main/java/sample/H2ConsoleInitializer.java

@@ -24,7 +24,6 @@ import org.springframework.web.WebApplicationInitializer;
 
 public class H2ConsoleInitializer implements WebApplicationInitializer {
 
-	@Override
 	public void onStartup(ServletContext servletContext) throws ServletException {
 		servletContext.addServlet("h2console", new WebServlet()).addMapping("/console/*");
 	}