main.go: add argument parsing for config path

main.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"flag"
 	"net/http"
 	"github.com/BurntSushi/toml"
 )
@@ -12,7 +13,11 @@ type tomlConfig struct {
 var config tomlConfig
 
 func main() {
-	_, err := toml.DecodeFile("config.toml", &config)
+	var configPath string
+	flag.StringVar(&configPath, "config", "config.toml", "path to config file")
+	flag.Parse()
+
+	_, err := toml.DecodeFile(configPath, &config)
 	if err != nil {
 		panic(err)
 	}