Added OKCOIN REST lending functionality.
Added OKCOIN REST lending functionality.

thrasher-/gocryptotrader,dolanor/gocryptotrader,thrasher-/gocryptotrader,snipesjr/gocryptotrader,snipesjr/gocryptotrader,thrasher-/gocryptotrader,thrasher-/gocryptotrader,thrasher-/gocryptotrader,snipesjr/gocryptotrader,snipesjr/gocryptotrader,jmaurice/gocryptotrader