title: Specify the assets output directory when building in development mode
body: <p>I'm using the Vue CLI to build my application into one of my existing php projects. In case to work with generated files in php, I need to move the assets to the <code>../public/assets/</code> directory. Unfortunately, this does not seem to work in development environment (production mode works just fine, but I'd really need to test the integration of vue in the php app).</p>
  
  <p>Am I doing something wrong or is it a known restriction?</p>
  
  <p>Here's the config:</p>
  
  <pre><code>// vue.config.js
  module.exports = {
      outputDir: '../public',
      assetsDir: './assets',
      indexPath: './views/index.html'
  };
  </code></pre>