Make NetworkStats a pointer to help the callers ignore that stats if it cannot be returned for any reason.

Docker-DCO-1.1-Signed-off-by: Vishnu Kannan <vishnuk@google.com> (github: vishh)
Do not mark any network stats as 'omitempty' since the value '0' is legal for those stats.

Docker-DCO-1.1-Signed-off-by: Vishnu Kannan <vishnuk@google.com> (github: vishh)
Merge pull request #119 from vishh/fix_network_stats

Minor fixes to network stats
Add busybox rootfs so we can run containers

make sh will spawn a new container using the minimal.json file inside
busybox and you don't even know what is going on.
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@docker.com> (github: crosbymichael)
Merge pull request #120 from crosbymichael/add-tests1

Add busybox rootfs so we can run containers
Add missing "--rm" on "make sh"

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Merge pull request #122 from tianon/makefile-rm

Add missing "--rm" on "make sh"
Fix veth network stats. Tx on the host vETH is ingress traffic and not egress.

Docker-DCO-1.1-Signed-off-by: Vishnu Kannan <vishnuk@google.com> (github: vishh)