title: Run a npm script from gulp task
body: <p>How to run a npm script command from inside a gulp task?</p>
  
  <p>package.json</p>
  
  <pre><code>"scripts": 
  {
      "tsc": "tsc -w"
  }
  </code></pre>
  
  <p>gulpfile.js</p>
  
  <pre><code>gulp.task('compile:app', function(){
    return gulp.src('src/**/*.ts')
      .pipe(/*npm run tsc*/)
      .pipe(gulp.dest('./dist'))
      .pipe(connect.reload());
  });
  </code></pre>
  
  <p>I want to do this because running <code>npm run tsc</code> does not give me any error but if I use <code>gulp-typescript</code> to compile <code>.ts</code> then I get bunch of errors.</p>