Add Transaction log detection for ERC20 Tokens

Enable Transaction Log pickup for ERC20 Tokens.

You can search for Approve, Transfer and common other DeFi events.

Check out the implementation in ERC721Token and ERC1155Token and do something along those lines; the reason being there will be another upgrade to find the contract constructor and use that to help sync logs, which should be able to slot easily into the methods used to pick up logs in Tokens.