Give priority to custom views over generic matching patterns on AdminSite.

I am not sure on what Django version this became an issue, but my custom view, with URL "insertion_report/", was not reached, because Django matched the request with:

            url(r'^(?P<app_label>\w+)/$',
                wrap(self.app_index),
                name='app_list')

(contrib/admin/sites.py:238, on Django 1.6.1)

that came first in the urlpatterns chain.