Remove admin.autodiscover() for URLconf example

[aaugustin]

I suggest to replace:

from ratelimitbackend import admin

admin.autodiscover()

urlpatterns += patterns('',
    (r'^admin/', include(admin.site.urls)),
)

with:

from ratelimitbackend import admin

urlpatterns += [
    (r'^admin/', include(admin.site.urls)),
]

which is the recommended style as of Django 1.7, the oldest currently
supported Django version.