Check stdin option when wrapping

This PR makes it possible to start and stop nodemon apps using tools such as `gulp` or `grunt`.

```js
var nodemon = require('nodemon');

nodemon({
  script: 'index.js',
  ext: 'js',
  restartable: false,
  stdin: false
});

nodemon.on('start', function () {
  console.log('Start');

  setTimeout(function() {
    nodemon.emit('quit');
  }, 1000);
});
```