[libvirt] [Patch][RFC] Fine grained access control in libvirt by rbac (0/3)

The series of patches introduces a fine grained access control to libvirt. They enable libvirt to enforce users what operations to invoke in role-based way. Our team found that Konrad and Daniel have similar interest to ours. Comments and suggestions are very welcome. Patches: - Embedding hooks in libvirt (1/3) - Access control library (2/3) - Example policy files (3/3)