Reactivate certificate check

client.go

 package main
 
 import (
-	"crypto/tls"
 	"encoding/json"
 	"fmt"
 	"io/ioutil"
@@ -62,11 +61,7 @@ const (
 )
 
 var (
-	// TODO fix certs
-	tr = &http.Transport{
-		TLSClientConfig: &tls.Config{InsecureSkipVerify: true},
-	}
-	client = &http.Client{Transport: tr}
+	client = &http.Client{}
 )
 
 func failOnError(err error, msg string) {