Add support batch

[baltazorbest]

Please add support batch for multi insert / update / delete / select.

For example: $tnt = Tarantool('localhost', 3301); $tnt->connect(); $batch = $tnt->batch(); $batch->insert(); $batch->update(); $batch->delete(); $batch->select(); $result = $batch->exec();

Result like: array { 'key' => array(result), 'key' => array(result) }