Added doc_serve signal
Renamed doc_serve signal to document_served
Added changelog entry for document_served signal
Merge pull request #206 from kaedroho/doc-serve-signal

Added document_served signal
add changelog note re Python 2.6 compatibility
Eliminate 'patterns' from wagtailadmin/urls.py as per https://code.djangoproject.com/ticket/22218
Eliminate 'patterns' from wagtailcore/urls.py as per https://code.djangoproject.com/ticket/22218
Eliminate 'patterns' from wagtaildocs/urls.py and admin_urls.py as per https://code.djangoproject.com/ticket/22218
Eliminate 'patterns' from wagtailembeds/urls.py as per https://code.djangoproject.com/ticket/22218
Eliminate 'patterns' from wagtailimages/urls.py as per https://code.djangoproject.com/ticket/22218
Eliminate 'patterns' from wagtailredirects/urls.py as per https://code.djangoproject.com/ticket/22218
Eliminate 'patterns' from wagtailsearch/urls as per https://code.djangoproject.com/ticket/22218
Eliminate 'patterns' from wagtailsnippets/urls.py as per https://code.djangoproject.com/ticket/22218
Eliminate 'patterns' from wagtailusers/urls.py as per https://code.djangoproject.com/ticket/22218
Add a register_admin_urls hook so that subapps of wagtailadmin can register their urlpatterns with wagtailadmin, avoiding the need for them to be defined in the project's urlconf