x-2.1.0: Merge commit '60f066ce32dc9ebfcaa4c7c96f70f1fb8609eac4'

* commit '60f066ce32dc9ebfcaa4c7c96f70f1fb8609eac4': (1106 commits)
  1.18.862
  therock sign() headers with Content-Type refix #5414
  therock sign() headers with Content-Type fix #5414
  1.18.861
  1.18.860
  okcoinusd createRequest fix #5410
  fix #5407
  1.18.859
  okcoinusd/okex createMarketBuyOrder fix #5405
  1.18.858
  skip mixcoins on travis during the maintenance
  okex v1 markets futures type fix
  1.18.857
  Fixed aiohttp_trust_env var not being passed.
  1.18.856
  kucoin parseLedgerEntry minor edit
  1.18.855
  kucoin parseLedgerEntry id minor fixup
  fix the parse_transaction_status for huobipro
  add has fetchLedger
  ...

# Conflicts:
#	package.json
#	python/ccxt/bitbank.py