This patch starts "ansiblization" of the image building script, while
also cleaning it up. More importantly, it adds check and gate jobs
that verify the same playbooks as used in the post job.
Also correct source-repository for ironic-python-agent to use the
project name, not the old element name.
Change-Id: I9a404b24f95e47c84b22d4739fcf2b5b800886f9
