Added feature to bid/buy cryptocurrency using book orders from exchange. The idea, is to get rates from the top 2 (depending on the config settings) of book orders instead of tickers. This way we can offset the lags from the OHLCV data.

freqtrade/constants.py

@@ -65,6 +65,8 @@ CONF_SCHEMA = {
                     'maximum': 1,
                     'exclusiveMaximum': False
                 },
+                'use_book_order': {'type': 'boolean'},
+                'book_order_top': {'type': 'number', 'maximum':20,'minimum':1}
             },
             'required': ['ask_last_balance']
         },