title: busboy fileSize limit event is not being called
body: <p>I'm uploading a file using express into a MongoDb. All is working fine, but now I'm trying to set a size limit.
  Setting <code>busboy</code> configuration as  <a href="https://www.npmjs.com/package/busboy" rel="nofollow">busboy</a> site declares:</p>
  
  <pre><code> var busboy = new Busboy({ headers: req.headers,  limit: { files: 1, fileSize: 50000 }  });
  </code></pre>
  
  <p>then:</p>
  
  <pre><code>file.on('limit', function(data) {                                               
       console.log("LIMIT");
  });
  </code></pre>
  
  <p>By the way, I can try to find a workaround by stopping everything when the data chucks add up to the limit size.</p>
  
  <pre><code>file.on('data', function(data) {                                          
     fileSize+=data.length;
      if (fileSize&gt;50000){
          //limit reached 
     }                         
  });
  </code></pre>