chore(requirements): update backoff library

mboersma · mboersma · commit 74d16af9ad4d · 2017-02-07T09:45:02.000-07:00
See https://github.com/litl/backoff/blob/master/CHANGELOG.md#v140---2017-02-05
diff --git a/rootfs/requirements.txt b/rootfs/requirements.txt
@@ -1,5 +1,5 @@
 # Deis controller requirements
-backoff==1.3.2
+backoff==1.4.0
 Django==1.10.5
 django-auth-ldap==1.2.8
 django-cors-middleware==1.3.1
