message: move kv values to shared_blob
diff: @@ -62,7 +62,7 @@ namespace eosio { namespace chain {
  table_id t_id;
  uint64_t primary_key;
  account_name payer = 0;
  - shared_string value;
  + shared_blob value;
  };
  using key_value_index = chainbase::shared_multi_index_container<
  