Better debugging options and other minor fixes

- Made state dump made (mostly) compatible with pyethereum and proper JSON output.
- Make state dump configurable for individual blocks
- Add option for vm dump for specific block (compatible with c++ and Go)
- Move most of the WalletTransaction code out of WorldManager and into the Wallet class
- Verify and validate postTxState after apply every tx to the state.
- Return gasUsed after every tx
- Update peer name (example: EthereumJ/v0.5.3/Nick/Windows/Java)