docs/installation/google: update to use container-vm images

Docker-DCO-1.1-Signed-off-by: Johan Euphrosine <proppy@google.com> (github: proppy)

rebased by

Docker-DCO-1.1-Signed-off-by: Sven Dowideit <SvenDowideit@home.org.au> (github: SvenDowideit)
Merge pull request #6100 from SvenDowideit/pr_out_docs_installation_google_update_to_use_container_vm_images

docs/installation/google: update to use container-vm images
Added a new method cgroups.GetStats() which will return a cgroups.Stats object which will contain all the available cgroup Stats.
Remove old Stats interface in libcontainers cgroups package.
Changed Stats to use unit64 instead of int64 to prevent integer overflow issues.
Updated unit tests.

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