title: Command not found after npm install in zsh
body: <p>I'm having some problems installing <a href="http://vowsjs.org" rel="noreferrer">vows</a> via npm in zsh. Here's what I get. I tried installing it with and without the -g option. Do you have any idea what's wrong here?</p>
  <pre><code>[❤  ~/Desktop/sauce-node-demo:master] npm install -g vows
  npm http GET https://registry.npmjs.org/vows
  npm http 304 https://registry.npmjs.org/vows
  npm http GET https://registry.npmjs.org/eyes
  npm http GET https://registry.npmjs.org/diff
  npm http 304 https://registry.npmjs.org/eyes
  npm http 304 https://registry.npmjs.org/diff
  /usr/local/share/npm/bin/vows -&gt; /usr/local/share/npm/lib/node_modules/vows/bin/vows
  vows@0.6.4 /usr/local/share/npm/lib/node_modules/vows
  ├── eyes@0.1.8
  └── diff@1.0.3
  [❤  ~/Desktop/sauce-node-demo:master] vows
  zsh: command not found: vows
  </code></pre>