f2922c5c1f
Add a namespace object interface for somewhat cleaner code when creating and switching between network namespaces. All created namespaces are now mounted in /var/run/netns to ensure they have persistent inodes and paths that can be passed around between plugin components without relying on the current namespace being correct. Also remove the thread-locking arguments from the ns package per https://github.com/appc/cni/issues/183 by doing all the namespace changes in a separate goroutine that locks/unlocks itself, instead of the caller having to track OS thread locking.