scheduler: Allow co-locating containers that share outbound ports
scheduler: Allow co-locating containers that share outbound ports

Before, all containers that were connected in either direction to the
public internet were placed exclusively. However, the operating system
can handle multiple outbound connections to the same port fine.

Containers with inbound connections on the same port are still placed on
different machines.

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