Ability to log rejected transactions
Somewhat related to #198 as it increases amount of information we have about Hive at hand (without putting a lot of effort each time to debug stuff) Transactions might be valid and rejected for some reason and we would like to know that this happened and why. It might reach the node while being already expired, or it might not have enough RC until it expire (behavior that might change with #197 (closed)), or not enough free space in blocks (postponed) until it expire.