adding a bootstrap job. It should bring in the full dependencies of ROS ...

...not just the python tools now. This needs to be run before kicking off any release jobs.

@dirk-thomas This is a rough approximation of what needs to happen. I wasn't sure where this would best fit into the architecture. 

This or equivalent is needed to land: https://github.com/ros-infrastructure/buildfarm_deployment/pull/10
How will this be configurable?