* remove obsolete helper functions and make _state a public member.
* remove function assertions
* revert worker() changes
* Update pytest from 3.4.2 to 3.5.0
* Adapt exchange functions to ccxt API
Remove get_market_summaries and get_wallet_health, add exception handling
* Add NetworkException
* Change pair format in constants.py
* Add tests for exchange functions that comply with ccxt
* Remove bittrex tests
* Remove Bittrex and Interface classes
* Add retrier decorator
* Remove cache from get_ticker
* Remove unused and duplicate imports
* Add keyword arguments for get_fee
* Implement 'get_pair_detail_url'
* Change get_ticker_history format to ccxt format
* Fix exchange urls dict, don't need to initialize exchanges
* Add "Using Exchange ..." logging line
* replace pymarketcap with coinmarketcap
* fix tests to use coinmarketcap instead of pymarketcap
* use arraypos 0
* update setup.py from pymarketcap to coinmarketcap
* Add test to check for unsupported Crypto currency
- Update, clean, and improve code coverage on main.py
- Move bot trading logic into Freqtradebot() class
- Move unit tests to test_freqtradebot, add more coverage tests
