Added MIT license text to ccxt.py base file
Added MIT license text to ccxt.py base file

[ci-skip]
tritoanst/ccxt,aiueogawa/ccxt,tritoanst/ccxt,thijstriemstra/ccxt,thijstriemstra/ccxt,thijstriemstra/ccxt,aiueogawa/ccxt,aiueogawa/ccxt,thijstriemstra/ccxt,ccxt/ccxt,ccxt/ccxt,ccxt/ccxt,tritoanst/ccxt,ccxt/ccxt,aiueogawa/ccxt,tritoanst/ccxt,ccxt/ccxt