title: TypeScript error on compilation with webpack
body: <p>I am getting an error with typescript compilation and I have no clue where its coming from - I have tried many different combinations of tsconfig.json setups but I always get the same two errors from webpack-env.</p>
  
  <pre><code>(gec) ➜  optim ./node_modules/.bin/webpack --config webpack.config.js
  ts-loader: Using typescript@1.8.10 and /home/bischoff_s/Code/optim/tsconfig.json
  Hash: 0e608742cc4dff532c9a
  Version: webpack 1.13.1
  Time: 3182ms
                              Asset      Size      Chunks             Chunk Names
       main-0e608742cc4dff532c9a.ts   5.09 MB  0, 1, 2, 3  [emitted]  main
  polyfills-0e608742cc4dff532c9a.ts  25 bytes     1, 2, 3  [emitted]  polyfills
        app-0e608742cc4dff532c9a.ts  25 bytes     2, 1, 3  [emitted]  app
     vendor-0e608742cc4dff532c9a.ts   3.63 kB     3, 1, 2  [emitted]  vendor
      + 329 hidden modules
  
  ERROR in /home/guy/Code/optim/typings/globals/webpack-env/index.d.ts
  (176,13): error TS2403: Subsequent variable declarations must have the same type.  Variable 'require' must be of type 'NodeRequire', but here has type 'RequireFunction'.
  
  ERROR in /home/guyCode/optim/typings/globals/webpack-env/index.d.ts
  (225,13): error TS2403: Subsequent variable declarations must have the same type.  Variable 'module' must be of type 'NodeModule', but here has type 'Module'.
  </code></pre>
  
  <p>Here is my tsconfig.json</p>
  
  <pre><code>{
      "compilerOptions": {
          "target": "es5",
          "module": "commonjs",
          "emitDecoratorMetadata": true,
          "experimentalDecorators": true,
          "sourceMap": true,
          "noEmitHelpers": true
      }
  </code></pre>
  
  <p>}</p>