Modify bankAccount validation in quickstart-js to reflect api

The bankAccount validation examples in the quickstart are not correct.
```js
balanced.bankAccount.validate({
   bank_code:'321174851',
   account_number:'9900000000',
   name:'John Doe'
})
```

should read
```js
balanced.bankAccount.validate({
   routing_number:'321174851',
   account_number:'9900000000',
   name:'John Doe'
})
```