Update djangorestframework from 3.7.7 to 3.8.0 (#3385)
Update djangorestframework from 3.7.7 to 3.8.0 (#3385)

http://www.django-rest-framework.org/topics/3.8-announcement/
http://www.django-rest-framework.org/topics/release-notes/#380
KWierso/treeherder,edmorley/treeherder,KWierso/treeherder,KWierso/treeherder,KWierso/treeherder,edmorley/treeherder,edmorley/treeherder,edmorley/treeherder