title: gulp-shell 'karma is not recognized an an internal or external command...'
body: <p>I'm using gulp to concat, minify, and then test all of my JS. I want to include karma in there as well, but I can't seem to get gulp-shell 'karma start karma.conf.js' to work properly. Karma is added to PATH, as I'm able to run that command from the same working directory as the gulpfile in Windows Shell without any problems. I can also run other commands correctly, like 'ls', 'pwd', 'npm --version', etc but for some reason it doesn't recognize 'karma'.</p>
  
  <p>I have also gotten this running on OSX properly, so it's an issue local to my machine. Any help would be appreciated.</p>
  
  <pre><code>gulp.task('run-karma', shell.task(['karma start karma.conf.js']));
  </code></pre>
  
  <p>error is </p>
  
  <pre><code> 'karma' is not recognized as an internal or external command, 
   operable program or batch file.
   Error in plugin 'gulp-shell' Message:
     Command 'karma start karma.conf.js' failed with exit code 1
  </code></pre>