Move to final release of CentOS7 images
Move to final release of CentOS7 images

This is the final released image; it is the same one deployed in many
cloud provers such as HP and AWS.  It is also safe from all known
vulnerabilities up to its release

Change-Id: Ib8ba561662d2a98da55eb292b850dc019226dd59

rdo-management/diskimage-builder,eantyshev/diskimage-builder,switch-ch/diskimage-builder,openstack/diskimage-builder,takahashinobuyuki/diskimage-builder,eantyshev/diskimage-builder,switch-ch/diskimage-builder,takahashinobuyuki/diskimage-builder,NaohiroTamura/diskimage-builder,zioproto/diskimage-builder,CSC-IT-Center-for-Science/diskimage-builder,rdo-management/diskimage-builder,JioCloud/diskimage-builder,CSC-IT-Center-for-Science/diskimage-builder,zioproto/diskimage-builder,NaohiroTamura/diskimage-builder,varunarya10/diskimage-builder,openstack/diskimage-builder,varunarya10/diskimage-builder,JioCloud/diskimage-builder