Fix ramdisk-image-create
Fix ramdisk-image-create

ELEMENTS_DIR env var was not being set by lib/ramdisk-defaults.
This caused ramdisk-image-create to fail.

Change-Id: I25ec43feddb8ef546dba83a77b8488fee98d4a17

agroup/tripleo-puppet-elements,citrix-openstack-build/diskimage-builder,qwefi/tripleo-image-elements,zioproto/diskimage-builder,qwefi/tripleo-image-elements,rdo-management/diskimage-builder,openstack/tripleo-image-elements,switch-ch/diskimage-builder,switch-ch/diskimage-builder,agroup/tripleo-puppet-elements,NaohiroTamura/diskimage-builder,agroup/tripleo-puppet-elements,takahashinobuyuki/diskimage-builder,openstack/diskimage-builder,qwefi/tripleo-image-elements,rdo-management/diskimage-builder,radez/tripleo-image-elements,qwefi/tripleo-image-elements,agroup/tripleo-puppet-elements,eantyshev/diskimage-builder,JioCloud/diskimage-builder,CSC-IT-Center-for-Science/diskimage-builder,rdo-management/tripleo-image-elements,varunarya10/diskimage-builder,radez/tripleo-image-elements,eantyshev/diskimage-builder,rdo-management/tripleo-image-elements,NaohiroTamura/diskimage-builder,zioproto/diskimage-builder,takahashinobuyuki/diskimage-builder,citrix-openstack-build/diskimage-builder,openstack/diskimage-builder,CSC-IT-Center-for-Science/diskimage-builder,varunarya10/diskimage-builder,openstack/tripleo-image-elements,JioCloud/diskimage-builder,qwefi/tripleo-image-elements