Remove useless import
Once we switched to the native DurationField, we stopped needing the
durationfield package. (It's still in requirements/base.txt because
older migrations import from it.)
@@ -8,8 +8,6 @@ from django.core.urlresolvers import reverse_lazy
from django.db import models
from django.utils.translation import ugettext_lazy as _
-from durationfield.db.models.fields.duration import DurationField
-
RESOURCE_LANGUAGES = copy.copy(LANGUAGES)
RESOURCE_LANGUAGE_CODES = [lang[0] for lang in RESOURCE_LANGUAGES]
