title: yarn - install modules in a specific directory
body: <p>When I do <code>$ yarn install</code>, I see that <code>./node_modules</code> directory gets created and modules are installed in that directory.</p>
  
  <p>I also get that <code>--modules-folder ./directory_location</code> exists, to install in a specific directory one time.</p>
  
  <p>Is there an option to always use a specific directory to install in package.json configuration?</p>