CPULimiteHost.popen(): set cgroup and (optionally) RT priority
Add support for attaching to network namespace using setns(2)
Removed unused variable.
Support for control-C. Finally.
I've changed the way things work a bit:
1. netns is replaced by mnexec, a general-purpose mininet helper.
2. For interactive commands, we now use mnexec -p, which prints out the pid, so we can kill it when someone hits control-C!...