LXC: adapt hv for newer lxc userspace tools

Currently hv_lxc depends on the behavior and output of older LXC tools,
which have since changed, making it unable to function in current
distributions (e.g. Debian wheezy).

Adapt the tools and expectation for the output and make it into a
working state again, at least for LXC 0.8.0.

LXC tools seem to be split into two categories: the actual, binary lxc
tools, plus a set of shell scripts to provide a higher-level interface.
Ganeti doesn't need the latter and the shell scripts make some
assumptions (like /var/lib/lxc) so remove the only reference to such a
shell script (lxc-ls).

While at it, remove a few comments about "current (Spring 2010)
distributions" that do not apply anymore.

This is a backwards-incompatible change, meaning it won't work on
systems with older LXC userspace. However, hv_lxc is experimental anyway
and there's virtually no documentation about it in the tree.

Signed-off-by: Faidon Liambotis <paravoid@debian.org>
Reviewed-by: Guido Trotter <ultrotter@google.com>