Rename Container -> Config.

Docker-DCO-1.1-Signed-off-by: Victor Marmol <vmarmol@google.com> (github: vmarmol)
Merge pull request #39 from vmarmol/rename-container

Rename Container -> Config.
Add User Namespace support to libcontainer.
Docker-DCO-1.1-Signed-off-by: Mrunal Patel <mrunalp@gmail.com> (github: mrunalp)