node.d.ts is unusable with this loader

Hey,

thanks for the great project. But unfortunately I have run into an issue. If you install the node.d.ts from definitelytyped.org the loader tries to resolve the `require` statements inside that file, even though they refer to definitions inside that file.

Excerpt from my config:

``` js
resolve: { extensions: ['', '.webpack.js', '.web.js', '.js', '.ts'] }
loaders: [
{
test: /\.ts?$/,
exclude: /node_modules/,
loader: 'babel!typescript-loader?noImplicitAny=true&target=es6!ts-jsx-loader'
}
]
```

The error is

```
Module build failed: Error: Cannot resolve module 'net.ts' in path/to/typings/node
```