Add a command line to setup/retrieve value of cgroup subsystem, lxc-cgroup -n <container name> <subsystem> [value]. If the value is specified, the subsystem is modified, if it is not specified, the value of the subsystem is returned

	lxc.cgroup.xxx = yyy
where xxx is a cgroup subsystem (eg. cpu.shares) and the yyy is the value to
be set.

The lxc-execute command will automatically create a new container and destroy
it when it dies. If a configuration file is specified and the container does
not exists, the container is created with the configuration file and destroyed
when it dies.