Verify CEX assets

[ghost]

#99

[raladev]

• no error throwing for unexisted pair if two assets are exist on centralized exchange

Steps:

0. binance has BTC/DAI pair, but not DAI/BTC
1. bash xud.sh -b arby --arby.disabled false --arby.live-cex false --arby.base-asset DAI --arby.quote-asset BTC --arby.cex Binance

CEX_BASEASSET: DAI
CEX_QUOTEASSET: BTC
TEST_CENTRALIZED_EXCHANGE_BASEASSET_BALANCE: 123
TEST_CENTRALIZED_EXCHANGE_QUOTEASSET_BALANCE: 321
2020-10-06 01:38:59.5959 [Centralized] info: Base asset balance 0.00842727 and quote asset balance 0.00040029
2020-10-06 01:38:59.5959 [OpenDEX] trace: Base asset balance 709.921875 (maxinbound: 548.828125, maxoutbound: 709.921875) and quote asset balance 2.5 (maxinbound: 2.4499095, maxoutbound: 2.45).
2020-10-06 01:39:00.000 [Centralized] trace: DAIBTC established connection to wss://stream.binance.com:9443/ws/daibtc@aggTrade
2020-10-06 01:39:00.000 [Centralized] trace: heartbeat from DAIBTC socket
2020-10-06 01:39:30.3030 [OpenDEX] trace: Base asset balance 709.921875 (maxinbound: 548.828125, maxoutbound: 709.921875) and quote asset balance 2.5 (maxinbound: 2.4499095, maxoutbound: 2.45).

[ghost]

* no error throwing for unexisted pair if two assets are exist on centralized exchange

Should be fixed now. The issue was that on the API level the trading pair existed, but was marked as inactive.