Fix flags support

Signed-off-by: Marcus Noble <github@marcusnoble.co.uk>

main.go

@@ -21,10 +21,13 @@ var (
 	port     int
 )
 
-func main() {
+func init() {
 	flag.IntVar(&interval, "interval", 30, "Duration, in minutes, between speedtest runs")
 	flag.IntVar(&port, "port", 9091, "The port to listen on")
+	flag.Parse()
+}
 
+func main() {
 	go (func() {
 		for {
 			checkSpeed()