Add the Interface config APIs

Add the Interface config APIs
* configure.in include/libvirt/libvirt.h[.in]
  include/libvirt/virterror.h qemud/remote.c
  qemud/remote_dispatch_args.h qemud/remote_dispatch_prototypes.h
  qemud/remote_dispatch_ret.h qemud/remote_dispatch_table.h
  qemud/remote_protocol.[chx] src/Makefile.am src/datatypes.c
  src/datatypes.h src/driver.h src/libvirt.c src/remote_internal.c
  src/virterror.c src/libvirt_private.syms src/libvirt_public.syms:
  Add the Interface config APIs and remote stubs for those, patch
  by Laine Stump
* AUTHORS: add Laine
daniel