- Allows us to fetch receipts by block and persist even when associated transaction is unknown. (The associated transaction can still be derived from the tx_hash column at query time, but is an expensive operation to require for inserts).
* Upgrade go-ethereum to v1.8 * Add Node Info for parity nodes * Upgrade start_private_blockchain to use v1.8
- Adds interfaces for developers to build handlers that update data in response to log events - Resolves #29
