title: warning when executing npm install
body: <p>After installation of npm (version 4.1.2 on Windows 10) I executed "npm install". But I get the following warning:</p>
  
  <blockquote>
    <p>npm WARN optional SKIPPING OPTIONAL DEPENDENCY: fsevents@^1.0.0
    (node_modules\chokidar\node_modules\fsevents): npm WARN notsup
    SKIPPING OPTIONAL DEPENDENCY: Unsupported platform for
    fsevents@1.0.17: wanted {"os":"darwin","arch":"any"} (current:
    {"os":"win32","arch":"x64"})</p>
  </blockquote>
  
  <p>Any ideas why?</p>