set_cgroup_item takes a pointer to a running container, a cgroup subsystem
name, and a char *value and it mimicks
	'lxc-cgroup -n containername subsys value'
get_cgroup_item takes a pointer to a running container, a a cgroup
subsystem name, a destination value * and the length of the value being
sent in, and returns the length of what was read from the cgroup file.
If a 0 len is passed in, then the length of the file is returned.  So
you can do

	len = c->get_cgroup_item(c, "devices.list", NULL, 0);
	v = malloc(len+1);
	ret = c->get_cgroup_item(c, "devices.list", v, len);

to read the whole file.

This patch also disables the lxc-init part of the startone test, which
was failing because lxc-init has been moved due to multiarch issues.
The test is salvagable, but saving it was beyond this effort.
Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>