title: Yeoman cannot find 'underscore.string' when using generator for web
body: <p>I'm on Mac OSX Yosemite Version 10.10.3 and I'm very new to the process of developing web apps. I have bower, npm, and yeoman installed on my system, but the webapp generator keeps on returning an error when I'm trying to generate my scaffolding.</p>
  
  <pre><code>Justins-iMac-2:testapp JRS$ yo webapp
  module.js:338
  throw err;
        ^
  Error: Cannot find module 'underscore.string'
  at Function.Module._resolveFilename (module.js:336:15)
  at Function.Module._load (module.js:278:25)
  at Module.require (module.js:365:17)
  at require (module.js:384:17)
  at Object.&lt;anonymous&gt; (/usr/local/lib/node_modules/generator-webapp/app/index.js:8:10)
  at Module._compile (module.js:460:26)
  at Object.Module._extensions..js (module.js:478:10)
  at Module.load (module.js:355:32)
  at Function.Module._load (module.js:310:12)
  at Module.require (module.js:365:17)
  at require (module.js:384:17)
  </code></pre>
  
  <p>Does anyone have an idea on how to resolve this issue?</p>