It is hard to know when disk images need to be rebuilt, and the
stackhpc.os-images role simply checks for the presence of the DIB output
directory to indicate that an image exists. In some cases, we may wish to force
the rebuilding of a deployment (IPA) image, when we know there are changes to
apply. This change adds a --force-rebuild argument to the following commands:
kayobe seed deployment image build
kayobe overcloud deployment image build
Change-Id: I580811a4f621df9445ef32773ca66bcf303dad9b
22cf08e882