Made batched_replaces_t and batched_writes_t use a std::vector<std::pair<int64_t, ...> > instead of a std::vector<...> for sharding/unsharding.
Made the batched operation responses carry the int64_t for resorting upon unsharding.
Made unsharding implemented, possibly got batched reads and writes working.
Fixed bug in rdb write_t::unshard with what type we boost::get.