Only import django.contrib.site if it's in use

Since django1.7, importing models for uninitialized apps is not
supported, so Site if the app has been configured/initialized.

analytical/templatetags/chartbeat.py

@@ -8,7 +8,6 @@ import json
 import re
 
 from django.conf import settings
-from django.contrib.sites.models import Site
 from django.core.exceptions import ImproperlyConfigured
 from django.template import Library, Node, TemplateSyntaxError
 
@@ -109,6 +108,7 @@ def _get_domain(context):
         if 'django.contrib.sites' not in settings.INSTALLED_APPS:
             return
         elif getattr(settings, 'CHARTBEAT_AUTO_DOMAIN', True):
+            from django.contrib.sites.models import Site
             try:
                 return Site.objects.get_current().domain
             except (ImproperlyConfigured, Site.DoesNotExist):  # pylint: disable=E1101

analytical/tests/test_tag_chartbeat.py

@@ -4,7 +4,6 @@ Tests for the Chartbeat template tags and filters.
 
 import re
 
-from django.contrib.sites.models import Site
 from django.http import HttpRequest
 from django.template import Context
 from django.test import TestCase
@@ -31,6 +30,7 @@ class ChartbeatTagTestCaseWithSites(TestCase):
         call_command("migrate", verbosity=0)
 
     def test_rendering_setup_site(self):
+        from django.contrib.sites.models import Site
         site = Site.objects.create(domain="test.com", name="test")
         with override_settings(SITE_ID=site.id):
             r = ChartbeatBottomNode().render(Context())

analytical/utils.py

@@ -3,7 +3,6 @@ Utility function for django-analytical.
 """
 
 from django.conf import settings
-from django.contrib.sites.models import Site
 from django.core.exceptions import ImproperlyConfigured
 
 
@@ -100,6 +99,7 @@ def get_domain(context, prefix):
         domain = getattr(settings, 'ANALYTICAL_DOMAIN', None)
     if domain is None:
         if 'django.contrib.sites' in settings.INSTALLED_APPS:
+            from django.contrib.sites.models import Site
             try:
                 domain = Site.objects.get_current().domain
             except (ImproperlyConfigured, Site.DoesNotExist):