* src/conf/domain_conf.c, src/conf/domain_conf.h: APIs for
  inserting/finding/removing virDomainLeaseDefPtr instances
* src/qemu/qemu_driver.c: Wire up hotplug/unplug for leases
* src/qemu/qemu_hotplug.h, src/qemu/qemu_hotplug.c: Support
  for hotplug and unplug of leases