Change django.utils.log.NullHandler to logging.NullHandler
Change django.utils.log.NullHandler to logging.NullHandler

django.utils.log.NullHandler was removed in Django 1.9. logging.NullHandler
wad added to Python standard library since 2.7 so we should use it now.

Change-Id: I38f3f1d592f5456efc7dc94c0677a0a594722fbd

noironetworks/horizon,noironetworks/horizon,ChameleonCloud/horizon,ChameleonCloud/horizon,ChameleonCloud/horizon,NeCTAR-RC/horizon,noironetworks/horizon,openstack/horizon,ChameleonCloud/horizon,NeCTAR-RC/horizon,openstack/horizon,NeCTAR-RC/horizon,openstack/horizon,NeCTAR-RC/horizon,noironetworks/horizon,openstack/horizon