title: webpack watch only watching entry
body: <p>I have a project setup using webpack 1.13.0 and it seems that when using <code>webpack --watch</code> it will only watch for changes in the entry point file.</p>
  
  <p>I have a project structure where I have js files in <code>$root\src</code> folder and the entry point file is <code>main.js</code> with the following:</p>
  
  <pre><code>import * as strings from 'strings'
  document.write(strings.sayHello('foobar'));
  </code></pre>
  
  <p>And strings is in the same folder with this</p>
  
  <pre><code>export const helloWorld = 'Hello, world!';
  
  export function sayHello(name) {
      return `Hello ${name}`;
  }
  
  export const foo = 'bar';
  export const bar = 'foo';
  </code></pre>
  
  <p>webpack.config.js contains this</p>
  
  <pre><code>module.exports = {
      entry: "./src/main.js",
      output: {filename: "./dist/bundle.js"},
  
      resolve: {root: __dirname + '/src'},
  
      module: {
        loaders: [
          {
            test: /\.js$/,
            exclude: /node_modules/,
            loader: "babel-loader",
            query: {
                presets: ['es2015']
            }
          }
        ]
      }
  };
  </code></pre>
  
  <p>Now if I make any changes to <code>main.js</code> it will recompile but changes to <code>strings.js</code> will not trigger a recompile. </p>