message: Make abi match currency.hpp
  account => key
  amount => quantity
diff: "fields": {
  "from": "account_name",
  "to": "account_name",
  - "amount": "uint64"
  + "quantity": "uint64"
  }
  },{
  "name": "account",
  "base": "",
  "fields": {
  - "account": "name",
  + "key": "name",
  "balance": "uint64"
  }
  }
  