Better log handling

[craig-willis]

We use the logspout container to pull logs from Docker containers within a namespace. Unfortunately this only works on a single host. We need a way to pull logs from containers across hosts (probably via Kubernetes API).

Also, it would be nice to have a clean way to pull logs that aren't sent to stdout/stderr. Some link known logs to /dev/stdxxx. Maybe do this for everything instead of requiring the container writer to do it?

[bodom0015]

It would also be nice, if possible, to show the progress of Docker pulls in our "Logs" functions of the API.

This could be a different issue, but seemed related to this one.