[rbridge] Consensus Check: Allow GVRP/MVRP

[Eastlake III Donald-LDE008]

This is a check via the mailing list to confirm or refute an apparent
consensus at the Vancouver meeting taken from the minutes of that
meeting:

      Remove any text prohibiting implementation
      of GVRP or MVRP on RBridges.

If no particular controversy arises over this in the next three weeks,
We will declare it to be the working group consensus.

Thanks,
Donald & Erik