title: TemplateSyntaxError : No module named braintree in paypal template?
body: <p>I am making a project that sells product and 
  I want to have a payment using paypal in my django. but I got this error :</p>
  
  <blockquote>
    <p>'billing_tags' is not a valid tag library: ImportError raised loading billing.templatetags.billing_tags: No module named braintree</p>
  </blockquote>
  
  <p>In my <code>settings.py</code> i have already put <code>'paypal.standard.ipn'</code> in <code>INSTALLED_APPS</code> and the <code>PAYPAL_RECEIVER_EMAIL</code>.</p>
  
  <p>When I check to my python shell..</p>
  
  <pre><code>&gt;&gt;&gt; from billing import get_integration
  &gt;&gt;&gt; get_integration("pay_pal")
  &lt;billing.integrations.pay_pal_integration.PayPalIntegration object at 0x9d41b0c&gt;
  </code></pre>
  
  <p>it means, it is working...</p>
  
  <p>In my <code>urls.py</code>, I have this:</p>
  
  <pre><code>from billing import get_integration
  pay_pal = get_integration("pay_pal")
  urlpatterns = patterns('',
      (r'^paypal-ipn-handler/', include(pay_pal.urls)),
  )
  </code></pre>
  
  <p>In my views.py :</p>
  
  <pre><code>from billing import get_integration
  from paypal.standard.forms import PayPalPaymentsForm
  def booking_save_page(request, id):
  .....
  form = BookTicketForm(request.GET)
  if form.is_valid():
      inst = Ticket.objects.create(
                 date_select = form.cleaned_data['date_select'],
                 product_name = product.name,
                 quantity = form.cleaned_data['quantity'],
                 totalcost = form.cleaned_data['totalcost'],
                 price = form.cleaned_data['price'],
                 first_name = form.cleaned_data['first_name'],
                 last_name = form.cleaned_data['last_name'],
                 contact = form.cleaned_data['contact'],
                 product = product,
                 client = client,
                 trans_code = code,
                 email = form.cleaned_data['email'],
                 memo = form.cleaned_data['memo'],
                 status = 'Pending',
                 created = now,
                 )
      pay_pal = get_integration("pay_pal")
      pay_pal.add_fields({
             "business": "ccfiel@gmail.com",
             "item_name": product.name,
             "invoice": inst.id,
             "notify_url": settings.BASE_DNS + "/paypal-ipn-handler/",
             "return_url": settings.BASE_DNS + str(client.id) + '/book/'+str(inst.id) +'/success/?booksaved=1',
             "cancel_return": settings.BASE_DNS + str(client.id) + '/?booksaved=0',
             "amount": inst.totalcost})
      form = PayPalPaymentsForm(initial=pay_pal)
      context = {"form": form}
      return render_to_response("pay_pay.html", context)
   ......
  </code></pre>
  
  <p>and my template <code>pay_pay.html</code> have only this:</p>
  
  <pre><code>&lt;h1&gt;Pay Here&lt;/h1&gt;
  {{ form.render }}
  </code></pre>
  
  <p>I think the problem is in rendering the <code>pay_pay.html</code> in my views... why i got this error:</p>
  
  <blockquote>
    <p>'billing_tags' is not a valid tag library: ImportError raised loading billing.templatetags.billing_tags: No module named braintree</p>
  </blockquote>
  
  <p>Does anyone have an idea about my situation?</p>