title: gulp browser-sync didn't work
body: <p>this is my gulpfile.js</p>
  
  <pre><code>var gulp = require('gulp'),
      browserSync = require('browser-sync');
  
  gulp.task('browser-sync', function() {
  browserSync({
      server: {
       baseDir: './',
     }
      })
  })
  </code></pre>
  
  <p>then i started "gulp browser-sync" and it listening on port 3000
  and i opened the url in browser.</p>
  
  <p>While editing html or css and document saved, the browser won't reload.</p>
  
  <p>If I used browser-sync to monitoring files, it works.</p>
  
  <p>Anything wrong with my gulpfile.js ?</p>