AEX9 account balances, contract logs with literal constructor

This release includes following improvements:

• showing of all AEX9 balances for account - https://github.com/aeternity/ae_mdw/#aex-9-contract-balances-for-account
• querying of contract logs with event=EventConstructorName instead of event hash - https://github.com/aeternity/ae_mdw/#querying-of-contract-logs