Update slice.proto

  rpc CreateSlice(context.Slice  ) returns (context.SliceId) {}

  rpc UpdateSlice(context.Slice  ) returns (context.SliceId) {}

  rpc DeleteSlice(context.SliceId) returns (context.Empty  ) {}

  rpc OrderSliceWithSLA(slice.TransportSlice) returns (slice.SliceStatus) {} // If slice with SLA already exists, returns slice. If not, it creates it.

}