chore(requirements): update django-auth-ldap to 1.2.9

See http://pythonhosted.org/django-auth-ldap/changes.html#v1-2-9-2017-02-14-fix-python-ldap-incompatibility

Author: mboersma

rootfs/requirements.txt

@@ -1,7 +1,7 @@
 # Deis controller requirements
 backoff==1.4.0
 Django==1.10.5
-django-auth-ldap==1.2.8
+django-auth-ldap==1.2.9
 django-cors-middleware==1.3.1
 django-guardian==1.4.6
 djangorestframework==3.5.3