analyze to use the ccxt OHLCV format

setup: remove bittrex and add requirement to ccxt

freqtradebot: update market summaries to ccxt format

freqtrade/analyze.py

@@ -44,12 +44,13 @@ class Analyze(object):
         :param ticker: See exchange.get_ticker_history
         :return: DataFrame
         """
-        columns = {'C': 'close', 'V': 'volume', 'O': 'open', 'H': 'high', 'L': 'low', 'T': 'date'}
-        frame = DataFrame(ticker) \
-            .rename(columns=columns)
-        if 'BV' in frame:
-            frame.drop('BV', 1, inplace=True)
-        frame['date'] = to_datetime(frame['date'], utc=True, infer_datetime_format=True)
+        cols = ['date', 'open', 'high', 'low', 'close', 'volume']
+        frame = DataFrame(ticker, columns=cols)
+
+        frame['date'] = to_datetime(frame['date'],
+                                    unit='ms',
+                                    utc=True,
+                                    infer_datetime_format=True)
         frame.sort_values('date', inplace=True)
         return frame