Update to libvirt 0.8.7
    
    - Preliminary support for VirtualBox 4.0
    - IPv6 support
    - Add VMware Workstation and Player driver driver
    - Add network disk support
    - Various improvements and bug fixes
    - from 0.8.6:
    - Add support for iSCSI target auto-discovery
    - QED: Basic support for QED images
    - remote console support
    - support for SPICE graphics
    - sysinfo and VMBIOS support
    - virsh qemu-monitor-command