Change ticker interval from minutes as integer to string (1m, 5m, 1h,...)

freqtrade/constants.py

@@ -16,12 +16,26 @@ class Constants(object):
     RETRY_TIMEOUT = 30  # sec
     DEFAULT_STRATEGY = 'default_strategy'
 
+    TICKER_INTERVAL_MINUTES = {
+        '1m': 1,
+        '5m': 5,
+        '15m': 15,
+        '30m': 30,
+        '1h': 60,
+        '2h': 120,
+        '4h': 240,
+        '6h': 360,
+        '12h': 720,
+        '1d': 1440,
+        '1w': 10080,
+    }
+
     # Required json-schema for user specified config
     CONF_SCHEMA = {
         'type': 'object',
         'properties': {
             'max_open_trades': {'type': 'integer', 'minimum': 1},
-            'ticker_interval': {'type': 'integer', 'enum': [1, 5, 30, 60, 1440]},
+            'ticker_interval': {'type': 'string', 'enum': list(TICKER_INTERVAL_MINUTES.keys())},
             'stake_currency': {'type': 'string', 'enum': ['BTC', 'ETH', 'USDT']},
             'stake_amount': {'type': 'number', 'minimum': 0.0005},
             'fiat_display_currency': {'type': 'string', 'enum': ['AUD', 'BRL', 'CAD', 'CHF',