title: How to shrinkwrap devDependencies, but not install them unless necessary?
body: <p>I have a bunch of <code>devDependencies</code> needed in order to run test suite and have production dependencies locked down with <code>npm shrinkwrap</code>. The problem is that when I run <code>npm install</code>, only production dependencies are installed, in order to install <code>devDependencies</code>, I have to remove npm-shrinkwrap.json and run it again. </p>
  
  <p>Now if shrinkwrap contains <code>devDependencies</code> as well, they get installed in production, where they are not required. Surely there should be some command line arguments to force only normal dependencies to be installed?</p>