Misc: admin media, pdf search path

Admin preview view now includes javascript tags provided by media,
There are dependencies added for backbone and underscore in that
specific admin page.

admin.py

@@ -15,6 +15,9 @@ class PageAdmin(admin.ModelAdmin):
     list_display = ['document', 'name', 'image', 'page_num']
     order_by = ['document', 'page_num']
 
+    class Media:
+        js = ("lib/underscore.js", "lib/backbone.js",)
+
     def get_urls(self):
         urls = super(PageAdmin, self).get_urls()
         my_urls = patterns('',
@@ -25,6 +28,7 @@ class PageAdmin(admin.ModelAdmin):
     def preview(self, request, pk):
         context = {}
         context['page'] = models.Page.objects.get(pk=pk)
+        context['media'] = self.media
 
         return TemplateResponse(request,
                                 'admin/pdfformfiller/page/preview.html',