title: Nothing happens using spawn gulp task to execute commands into subfolder
body: <p>Yesterday, I've been sent to a reference to use process_child.spawn for my need. I'd like gulp executing commands for me, to avoid typing commands concerning my dependency when I need to compile my main project.</p>
  
  <p>I got something that seems ok, any error into logs, but nothing happened, the way my commands wouldn't been executed.</p>
  
  <p>Any one with feedback about my code ? I got another task like this one to compile the dependency.</p>
  
  <pre><code>        var spawn = require("child_process").spawn;
          gulp.task("my-dependency-install", function(done) {
              spawn("ft", ["install"], {
                  cwd: "node_modules/app/my-dependency/"
              })
                  .on("error", function (err) {
                      throw err
                  })
                  .on("close", done);
          });
  </code></pre>
  
  <p>Thanks</p>