[libvirt] Add device operations support for libvirt (lxc)

[Heiher]

Hello,

Currently, libvirt is not support device operations for lxc.

This is a patch that add device operations support for libvirt 0.10.2.
1. lxcDomainAttachDevice
2. lxcDomainAttachDeviceFlags
3. lxcDomainDetachDevice
4. lxcDomainDetachDeviceFlags
5. lxcDomainUpdateDeviceFlags

In live mode, set devices.allow/deny to instance's cgroup and insert
disk config into current domain.
In config mode, just insert disk config into current domain.

This is part of 'Fix up attach/detach volume for nova (openstack)'.

Please see: https://bugzilla.redhat.com/show_bug.cgi?id=869259

-- 
Best regards!
Heiher
https://heiher.info