title: Rename file using custom npm script
body: <p>I want to make a script for my angular2 project that renames <code>README.md</code> to <code>README_2.md</code>. I installed  <code>"renamer" : "0.6.1"</code> and made this script:</p>
  
  <p><code>"renameMd": "renamer --find js/README.md --replace js/README_2.md"</code> in <code>package.json</code>, but it doesn't work. It gives me this error: <code>No input files supplied</code>.  How can I fix it ?</p>
  
  <p>PS: the file is located in the js folder.</p>