Feature: Add support to check whether an exchange supports automatic currency pair updates and if they don't, show a warning if the last currency pair update is >= 30 days

Also fix race condition in config get/set functions

exchanges/bittrex/bittrex.go

@@ -72,6 +72,7 @@ func (b *Bittrex) SetDefaults() {
 	b.ConfigCurrencyPairFormat.Delimiter = "-"
 	b.ConfigCurrencyPairFormat.Uppercase = true
 	b.AssetTypes = []string{ticker.Spot}
+	b.SupportsAutoPairUpdating = true
 }
 
 // Setup method sets current configuration details if enabled
@@ -96,6 +97,10 @@ func (b *Bittrex) Setup(exch config.ExchangeConfig) {
 		if err != nil {
 			log.Fatal(err)
 		}
+		err = b.SetAutoPairDefaults()
+		if err != nil {
+			log.Fatal(err)
+		}
 	}
 }