title: TypeError: __init__() got an unexpected keyword argument category
body: <p>I'm creating a basic app where my client can upload files through the app. It will then provide them with a URL so they can add images/pdf's etc to content in the website. What i'd like to do is have different category choices so when they upload a file they select the file type. So if they select 'images' the files will be uploaded into the images directory, and so on.</p>
  
  <p>Here is my code so far, i've gone to run python manage.py syncdb to add the models to the database but getting the above error.</p>
  
  <pre><code>CATEGORY_CHOICES = (
          ('Image', 'Image'),
          ('PDF', 'PDF')
      )
  
  file_type = models.CharField(category=CATEGORY_CHOICES, help_select="Please select a file type", default=IMAGE)
  file_upload = models.FileField(upload_to="media/images")
  
  def save(self, *args, **kwargs):    
      if self.file_type == 'Image':
          self.file.upload_to("media/images/filesApp")
      elif self.file_type == 'PDF':
          self.file.upload_to("media/pdf/filesApp")
      else:
          self.file.upload_to("media/filesApp")
  
      return super(File,self).save(*args, **kwargs)
  </code></pre>