title: How to add "$" in a Integer Field in Django in admin interface?
body: <p>I have a model like this:</p>
  
  <pre><code>class Category(models.Model):
      '''
          Category for tasks
      '''
      name = models.CharField(max_length=128)
      budget = models.IntegerField(help_text="Amount in US dollar ($)")
  
      class Meta:
          verbose_name_plural = "Categories"
  
      def __unicode__(self):
          return self.name
  </code></pre>
  
  <p>Data entry is fine. But when I show the attribute budget in admin interface like this:</p>
  
  <pre><code>class CategoryAdmin(admin.ModelAdmin):
      list_display = ('name', 'budget')
  </code></pre>
  
  <p>Instead of showing <code>100</code> I want to show <code>$100</code>. How can I do this?</p>