Add jenkins job builder tripleo script (based on pbr).
Add prepare_node_tripleo.sh which will be called by nodepool.
Add prepare_tripleo.sh script, based on the devstack script
but pulling in just the tripleo repositories with pull-tools
tripleo-incubator script.
Add tripleo stanza to nodepool itself.
Update site.pp with variables for tripleo authentication.
Add experimental pipeline to zuul's layout.yaml for this job on
tripleo-incubator.
Change-Id: I03433d08585ba3a783fe939264d7521cafa83e41
6fd82112e8