[kucoin] Re-instate trading support following platform 2.0 upgrade

[badgerwithagun]

Describe the bug
Constant stack traces in the log as Orko repeatedly fails to fetch exchange metadata for Kucoin.
Errors now resolved and getting public market data and balances, but no trade/history support yet.

To Reproduce
Attempt to use an API key on Kucoin and trade.

Expected behavior
All works.

Additional context
Kucoin has just upgraded to the 2.0 platform. I'm in the process of adding support for the 2.0 API to XChange (see knowm/XChange#2914). So far I only have public market data.

[badgerwithagun]

Balances in place. Now working on open orders.

[badgerwithagun]

Done.