Listen by default on port 3500

The master process will continue to start at port 3000.  In practice, this
ought to make conflicts between master-superviced processes and ones run by
hand less of an issue.

express/cli.ts

@@ -16,7 +16,7 @@ function parseListenAddress(listen: string | undefined): {
     port: number;
 } {
     const defaultHost = "127.0.0.1";
-    const defaultPort = 3000;
+    const defaultPort = 3500;
 
     if (!listen) {
         return { host: defaultHost, port: defaultPort };