Update AoC Plugin

They increased the "please don't hit our API more than once every x
minutes" to 15 instead of 10.
If the leaderboard update was for a previous year, note that in the
messages sent.

cmd/app.go

@@ -56,7 +56,8 @@ func (a *App) initialize() error {
 	}
 
 	// Now initialize the Slack stuff
-	var slackToken, slackDMid string
+	var slackToken string
+	// var slackDmid string
 	slackToken, err = a.m.getSlackToken()
 	if err != nil || slackToken == "" {
 		fmt.Print("Slack API Token: ")