Fix default config path

Instead of /etc/birdwatcher the config file location was assumed to
be in etc/birdwatcher relative to the working directory at execution.

birdwatcher.go

@@ -128,7 +128,7 @@ func (m *MyLogger) Write(p []byte) (n int, err error) {
 func main() {
 	bird6 := flag.Bool("6", false, "Use bird6 instead of bird")
 	workerPoolSize := flag.Int("worker-pool-size", 8, "Number of go routines used to parse routing tables concurrently")
-	configfile := flag.String("config", "etc/birdwatcher/birdwatcher.conf", "Configuration file location")
+	configfile := flag.String("config", "/etc/birdwatcher/birdwatcher.conf", "Configuration file location")
 	flag.Parse()
 
 	bird.WorkerPoolSize = *workerPoolSize