Adding file information to ease debugging.

[sourya7]

I've made some changes to the code to make it more easier to debug imported JS modules. However, I'm not really sure if what I've done is a good idea. I just wanted to know if you could review it and see if it seems reasonable. Right now, the code works for me with Nashorn. I haven't tried other engines but it should work if they support the load({script:, name:}) method.

You can see my changes at https://github.com/sourya7/jvm-npm/tree/patch-1

[romangromov]

@sourya7 works like a charm, thanks dude!