With Ubuntu 14.04 (trusty) you can simply add the following in the parent container config:
lxc.mount.auto = cgrouplxc.aa_profile = lxc-container-default-with-nestingreference: https://ubuntu.com/server/docs/containers-lxc(search for "nesting)
Make sure that you have pre-configured network before booting to avoid an long pause before the login screen appears!
HTH