ZB createOrder
ZB createOrder

Added swap orders to createOrder on ZB:
```
zb.createOrder (BTC/USDT:USDT, 1, 1, 0.002, 30000)
493 ms
{
  info: {
    code: '10000',
    desc: '操作成功',
    data: { orderId: '6900793317068578816', orderCode: null }
  },
  id: '6900793317068578816'
}
```

ccxt/ccxt,ccxt/ccxt,ccxt/ccxt,ccxt/ccxt,ccxt/ccxt