lxc: manually move NICs back to host after container stops

This prevents things like bridges from being destroyed by the kernel.

My hope is that just doing this will be enough to also ensure that
the device will be available to be renamed immediately, so that
we don't need to do a retry loop.

Tested with a dummy device.  renaming dummy0 to dummy5 in container,
then shutting down container, returns dummy0 to the host.

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>
lxc-autostart: Document -a and -g

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
lxc-autostart: Add a new --ignore-auto/-A flag

When passed, this flag will cause lxc-autostart to ignore the value of
lxc.start.auto.

This then allows things like: lxc-autostart -s -a -A

Which will select all containers regardless of groups (-a), regardless
of whether they are actually marked as auto-started (-A) and will shut
them down (-s).

Update our init scripts to use the new feature.

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
lxc-ls: Update help message to include fields

Instead of maintaining hardcoded lists, point everyone to --help and
have the current list of valid and default fields printed there.

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
lxc-ls: Add interfaces field

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
lxc-create: Require --template be passed

It's often been reported that the behavior of lxc-create without -t is a
bit confusing. This change makes lxc-create require the --template
option and introduces a new "none" special value which when set will
fallback to the old template-less behavior.

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>