This indicates the problem.
'$(?P<pk>[0-9]+)/$'
There shouldn’t be a dollar sign (which matches the end of the string) at the beginning of the pattern.
The problem is caused by the way you are including the urls.py. You currently have a dollar in the regex:
url(r'^$', include('feature.urls', namespace="feature")),
To fix the problem, remove the dollar from the regex.
url(r'^', include('feature.urls', namespace="feature")),