Add protype support for the build manager

This adds a `pe:jenkins:managed_uber_build` task to interact with our
hypothetical build manager. This job initializes the build manager for
a new build, and then calls `pe:jenkins:uber_build` with some extra
parameters set on the build in order to ensure the various packaging
runs know they are managed.

It also modifies the `pl:deb`, `pl:mock`, and `pe:local_sles` tasks so
that they will check in to the build manager on completion if a
managed build is running.

Things I hate:
* the begin/rescue/ensure stuff on all the tasks in order to make a
  failure callback is ugly as sin
* Managing the build parameters inside the `managed_uber_build` job is
  kind of nasty right now

Things TODO:
* Send status messages to the build manager instead of just
  success/failure