title: npm i chai --save-dev issue
body: <p>I'm using mocha to unit test for javascript<br>
  I'm using chai to manage assertion<br>
  After typing <code>npm i chai --save-dev</code> I obtain this error : </p>
  
  <pre><code>C:\Users\ABDELHAK&gt;npm i chai --save-dev
  npm ERR! Windows_NT 6.1.7601
  npm ERR! argv "C:\\Program Files\\nodejs\\\\node.exe" "C:\\Program Files\\nodejs\\node_modules\\npm\\bin\\npm-cli.js" "i" "chai" "--save-dev"
  npm ERR! node v0.10.18
  npm ERR! npm  v2.12.1
  npm ERR! file C:\Users\ABDELHAK\AppData\Roaming\npm-cache\chai\3.5.0\package\package.json
  npm ERR! code EJSONPARSE
  
  npm ERR! Failed to parse json
  npm ERR! Unexpected token '\u0000' at 1:1
  npm ERR!
  npm ERR! ^
  npm ERR! File: C:\Users\ABDELHAK\AppData\Roaming\npm-cache\chai\3.5.0\package\package.json
  npm ERR! Failed to parse package.json data.
  npm ERR! package.json must be actual JSON, not just JavaScript.
  npm ERR!
  npm ERR! This is not a bug in npm.
  npm ERR! Tell the package author to fix their package.json file. JSON.parse
  
  npm ERR! Please include the following file with any support request:
  npm ERR!     C:\Users\ABDELHAK\npm-debug.log
  </code></pre>
  
  <p>Note that mocha command works fine.</p>