title: Issue in create-react-app : The term 'create-react-app' is not recognized as the name of a cmdlet, function, script file, or operable program
body: <p>I have Node(v6.10.3) and npm(3.10.10) installed on my system. I installed <code>create-react-app</code> on it and it was successful. However, when i try to create a new project on my machine by simply running: <code>create-react-app sample-app</code>, it gives me following error:</p>
  
  <blockquote>
    <p>create-react-app : The term 'create-react-app' is not recognized as
    the name of a cmdlet, function, script file, or operable program.
    Check the spelling of the name, or if a path was included, verify that
    the path is correct and try again. 
    At line:1 char:1
    + create-react-app
    + ~~~~~~~~~~~~~~~~
        + CategoryInfo          : ObjectNotFound: (create-react-app:String) [], CommandNotFoundException
        + FullyQualifiedErrorId : CommandNotFoundException</p>
  </blockquote>
  
  <p>Have been working with the cli for years and never encountered this. Someone got any idea why this could be happening? Is it related to version of npm/node?</p>