Ethereum event listener

Examples of Ethereum event listen from geth or infura.

Run the script locally

• InstallNode.js version 6.3.1 or later;
• Clone or download source code to local disk;
• Install dependencies 'npm install';
• Start geth with: './geth --rpcapi "db,eth,net,web3,personal" --ws --wsaddr "localhost" --wsport "8545" --wsorigins "*" --identity "MyTestNode" --testnet --fast';
• Listen contract event from ropsten via geth 'node geth.js';
• Listen new block event from mainnet via infura 'node infura.js';

Infura don't support contract event listen at present, plz refer to #issue73