title: set directory for node_modules within gruntfile.js
body: <p>I would like to set the path of the node_modules directory within the gruntfile.js. I would like to have one central node_module directory for all my grunt projects.</p>
  
  <p>Is it possible to set the path for an external node_module directory?</p>
  
  <p><strong>Current setup (which works)</strong></p>
  
  <pre>
  projekt1
  --gruntfile.js
  --package.json
  --node_modules
  
  projekt2
  --gruntfile.js
  --package.json
  --node_modules
  </pre>
  
  <p><strong>Set up which I would like to have</strong></p>
  
  <pre>
  node_modules
  
  project1
  --gruntfile.js
  --package.json
  
  project2
  --gruntfile.js
  --package.json
  
  </pre>