NodeJS generated require() paths should mirror include paths

NodeJS uses file paths rather than namespaces to manage modules. However, the Thrift generated code ignores file paths.

I.e. if we have

foo.thrift:
include "../../shared.thrift";

It will turn into

foo_types.js:
var shared_types = require("./shared.thrift");

This forces us to put all generated node code in the same directory. It's problematic since if we happen to have

a/foo.thrift
b/foo.thrift

One file will have to overwrite the other...

I'm happy to make a patch for this, but unclear to me how much of a breaking change this would be for people, if it is at all.