stitch: Send node's stderr to stdout
stitch: Send node's stderr to stdout

Even if there weren't any errors when node parsed the user's
blueprint, we should still print stderr, in case there were
any warnings (e.g., about the deprecated connect function).

kklin/quilt,NetSys/quilt,kklin/kelda,NetSys/quilt,kklin/quilt,LuiseV/quilt,kklin/quilt,ejj/quilt-dev,kelda/kelda,kklin/quilt,kayousterhout/quilt,quilt/quilt,kelda/kelda,kelda/kelda,quilt/quilt,kayousterhout/quilt,quilt/quilt,NetSys/quilt,ejj/quilt-dev,kklin/kelda,LuiseV/quilt,ejj/quilt-dev,kayousterhout/quilt,LuiseV/quilt,LuiseV/quilt,kayousterhout/quilt,kklin/kelda,kklin/kelda,NetSys/quilt,NetSys/quilt,quilt/quilt,ejj/quilt-dev,kelda/kelda,LuiseV/quilt