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/gdax/gdax.go

@@ -70,6 +70,7 @@ func (g *GDAX) SetDefaults() {
 	g.ConfigCurrencyPairFormat.Uppercase = true
 	g.AssetTypes = []string{ticker.Spot}
 	g.APIUrl = gdaxAPIURL
+	g.SupportsAutoPairUpdating = true
 }
 
 // Setup initialises the exchange parameters with the current configuration
@@ -97,6 +98,10 @@ func (g *GDAX) Setup(exch config.ExchangeConfig) {
 		if err != nil {
 			log.Fatal(err)
 		}
+		err = g.SetAutoPairDefaults()
+		if err != nil {
+			log.Fatal(err)
+		}
 	}
 }