title: How to include all categories in one blog view
body: <p>I have 8 categories on my blog. I created view that will show only posts from choosen category. It works but i must create new view to every category. How can i include all categories in one view?</p>
  
  <p>My models:</p>
  
  <pre><code>class Category(models.Model):
      name = models.CharField(max_length=100)
      icon = models.ImageField(upload_to='icons',
                                blank=True)
  
  class Post(models.Model):
      author = models.CharField(max_length=25, blank=True, null=True)
      title = models.CharField(max_length=200)
      text = models.TextField()
      categories = models.ManyToManyField(Category, verbose_name='Categories')
      published_date = models.DateTimeField(
              default=timezone.now)
  </code></pre>
  
  <p>It is my view:</p>
  
  <pre><code>def sport(request):
      posts = Post.objects.filter(categories__name__exact="sport").order_by('-published_date')
      return render(request, 'blog/post_list.html', {'posts': posts})
  </code></pre>
  
  <p>You see, this view is only to category 'sport', to category 'politics' i have another view etc.</p>
  
  <p>In my template simple for loop:</p>
  
  <pre><code>{% for post in posts %}
      {{ post.title }}
  {% endfor %}
  </code></pre>
  
  <p>line in url</p>
  
  <pre><code>url(r'^sport$', views.sport, name='sport'),
  </code></pre>