Merge remote-tracking branch 'origin/new_exchange_config' into new_exchange_config

# Conflicts:
#	catalyst/exchange/ccxt/ccxt_exchange.py
#	catalyst/exchange/exchange.py
#	catalyst/exchange/utils/exchange_utils.py
#	catalyst/exchange/utils/serialization_utils.py
#	etc/requirements.txt

catalyst/exchange/utils/serialization_utils.py

@@ -6,6 +6,32 @@ import pandas as pd
 from catalyst.assets._assets import TradingPair
 from catalyst.constants import DATE_TIME_FORMAT
 from six import string_types
+from six import string_types
+
+from datetime import date, datetime
+from catalyst.constants import DATE_TIME_FORMAT, DATE_FORMAT
+from catalyst.assets._assets import TradingPair
+
+
+class ConfigJSONEncoder(json.JSONEncoder):
+    def default(self, obj):
+        """
+        JSON serializer for objects not serializable by default json code
+
+        Parameters
+        ----------
+        obj: Object
+
+        Returns
+        -------
+        str
+
+        """
+        if isinstance(obj, (datetime, date)):
+            return obj.floor('1D').strftime(DATE_FORMAT)
+
+        elif isinstance(obj, TradingPair):
+            return obj.to_dict()
 
 
 class ExchangeJSONEncoder(json.JSONEncoder):