Import django sorting-tags inside oscar. Change docs.

docs/source/_draft/getting_started/installation.rst

     'oscar.apps.search',
     'oscar.apps.catalogue_import',
 
-* Add the following to your `INSTALLED_APPS` if you intend to use the default oscar dashboard templates::
-
-    'django_sorting',
 
 * Add these to ``TEMPLATE_CONTECT_PROCESSORS``::
 

docs/source/getting_started.rst

     'oscar.apps.search',
     'oscar.apps.voucher',
 
-Add the following to your `INSTALLED_APPS` if you intend to use the default
-oscar dashboard templates::
-
-    'django_sorting',
-
 Add::
 
     from oscar.defaults import *

oscar/__init__.py

     'oscar.apps.dashboard.offers',
     'oscar.apps.dashboard.ranges',
     'oscar.apps.dashboard.vouchers',
-
-    'django_sorting',
 ]
 
 

oscar/templatetags/sorting_tags.py

+from django_sorting.templatetags.sorting_tags import *