restored tox in travis.yml
restored tox in travis.yml

ccxt/ccxt,aiueogawa/ccxt,ccxt/ccxt,tritoanst/ccxt,tritoanst/ccxt,aiueogawa/ccxt,aiueogawa/ccxt,tritoanst/ccxt,aiueogawa/ccxt,ccxt/ccxt,tritoanst/ccxt,ccxt/ccxt,ccxt/ccxt