Add support for centos 7 container

- Change to support multiple dists
- Fix LXC stop (lxc-stop -k)
- Add centos 7.0 support
Some additions to CentOS conf

- Fix lxc-console fails to get a login tty
- Move network conf at the right place
Merge pull request #8 from morucci/centos_support

Add support for centos 7 container