message: Allow empty action data on command line
diff: @@ -2304,9 +2304,11 @@ int main( int argc, char** argv ) {
  add_standard_transaction_options(actionsSubcommand);
  actionsSubcommand->set_callback([&] {
  fc::variant action_args_var;
  + if( !data.empty() ) {
  try {
  action_args_var = json_from_file_or_string(data, fc::json::relaxed_parser);
  } EOS_RETHROW_EXCEPTIONS(action_type_exception, "Fail to parse action JSON data='${data}'", ("data", data))
  + }
  auto arg= fc::mutable_variant_object
  ("code", contract_account)
  