local_settings needs 2.76% more ',' and an '_'
local_settings needs 2.76% more ',' and an '_'

While updating my local_settings.py file to more closely represent the
local_settings.py.example file, I noticed a small error (that's normally
commented out).

The VHD openstack image backend image format isn't being translated due
to a missing underscore.

I also noticed a few "missing" commas on the last element in a few lists
and dicts.

Change-Id: Ifef05c23921b88d7fc7f331cf293bbbd608af704
Closes-Bug: 1552955

bac/horizon,yeming233/horizon,noironetworks/horizon,yeming233/horizon,bac/horizon,noironetworks/horizon,wolverineav/horizon,yeming233/horizon,Mirantis/mos-horizon,django-leonardo/horizon,dan1/horizon-x509,coreycb/horizon,openstack/horizon,BiznetGIO/horizon,noironetworks/horizon,wolverineav/horizon,gerrive/horizon,BiznetGIO/horizon,yeming233/horizon,bigswitch/horizon,Mirantis/mos-horizon,sandvine/horizon,ChameleonCloud/horizon,bigswitch/horizon,wolverineav/horizon,BiznetGIO/horizon,redhat-openstack/horizon,bigswitch/horizon,sandvine/horizon,wolverineav/horizon,gerrive/horizon,django-leonardo/horizon,davidcusatis/horizon,Mirantis/mos-horizon,davidcusatis/horizon,coreycb/horizon,django-leonardo/horizon,redhat-openstack/horizon,django-leonardo/horizon,gerrive/horizon,NeCTAR-RC/horizon,NeCTAR-RC/horizon,dan1/horizon-x509,redhat-openstack/horizon,ChameleonCloud/horizon,dan1/horizon-x509,coreycb/horizon,coreycb/horizon,ChameleonCloud/horizon,dan1/horizon-x509,davidcusatis/horizon,openstack/horizon,noironetworks/horizon,redhat-openstack/horizon,gerrive/horizon,Mirantis/mos-horizon,bac/horizon,davidcusatis/horizon,openstack/horizon,NeCTAR-RC/horizon,openstack/horizon,sandvine/horizon,BiznetGIO/horizon,bigswitch/horizon,sandvine/horizon,bac/horizon,ChameleonCloud/horizon,NeCTAR-RC/horizon