Execute several TransactionBlock in a unique transaction

TransactionBlockList allows the execution of several TransactionBlock in the same Transaction

``` java
TransactionBlock transactionBlockA = new TransactionBlock() {
    @Override
    public void execute() throws JedisException {
        set("A", UUID.randomUUID().toString());
    }
};

TransactionBlock transactionBlockB = new TransactionBlock() {
    @Override
    public void execute() throws JedisException
    {
        set("B", UUID.randomUUID().toString());
        set("C", UUID.randomUUID().toString());
        }
    };

    TransactionBlockList transactionBlockList = new TransactionBlockList();
    transactionBlockList.add(transactionBlockA);
    transactionBlockList.add(transactionBlockB);

    Jedis redis = new Jedis("localhost");
    List<Object> results = redis.multi(transactionBlockList);
    redis.disconnect();
```

It is useful, for example, if you have abstracted all the persistence operations of an object in a DAO where all modification methods returns a TransactionBlock and you want to execute several calls in a unique transaction.