cluster: Allow for multiple GCE clusters within the same project
cluster: Allow for multiple GCE clusters within the same project

This actually uses the 'namespace' field passed into NewGCE() in the
way you would expect.

LuiseV/quilt,kklin/kelda,secant/quilt,quilt/quilt,tejasmanohar/quilt,NetSys/quilt,ZhongtianWang/quilt,kayousterhout/quilt,kklin/kelda,ejj/quilt-dev,mmussomele/quilt,kayousterhout/quilt,quilt/quilt,ejj/quilt-dev,ejj/quilt-dev,stevenlin598/quilt,ejj/quilt-dev,stevenlin598/quilt,PenguinToast/quilt,PenguinToast/quilt,LuiseV/quilt,tejasmanohar/quilt,stevenlin598/quilt,kklin/kelda,akshayknarayan/quilt,kklin/kelda,LuiseV/quilt,PenguinToast/quilt,NetSys/quilt,NetSys/quilt,secant/quilt,tejasmanohar/quilt,mmussomele/quilt,kelda/kelda,stevenlin598/quilt,kayousterhout/quilt,kayousterhout/quilt,kelda/kelda,PenguinToast/quilt,quilt/quilt,stevenlin598/quilt,mmussomele/quilt,LuiseV/quilt,kelda/kelda,ZhongtianWang/quilt,NetSys/quilt,ZhongtianWang/quilt,quilt/quilt,kklin/quilt,tejasmanohar/quilt,stevenlin598/quilt,secant/quilt,secant/quilt,akshayknarayan/quilt,kklin/quilt,kelda/kelda,LuiseV/quilt,NetSys/quilt,mmussomele/quilt,ZhongtianWang/quilt,mmussomele/quilt,akshayknarayan/quilt,kklin/quilt,secant/quilt,PenguinToast/quilt,mmussomele/quilt,kklin/quilt,akshayknarayan/quilt