Fix broken build because of go fmt issue

Fix broken build because of go fmt issue

```
$ make
>> checking code style
! gofmt -d $(find . -path ./vendor -prune -o -name '*.go' -print) | grep '^'
diff -u ./prober/utils_test.go.orig ./prober/utils_test.go
--- ./prober/utils_test.go.orig	2018-09-25 11:52:34.000000000 -0700
+++ ./prober/utils_test.go	2018-09-25 11:52:34.000000000 -0700
@@ -43,7 +43,7 @@
    publickey := &privatekey.PublicKey

    cert := x509.Certificate{
-		IsCA: true,
+		IsCA:                  true,
	BasicConstraintsValid: true,
	SubjectKeyId:          []byte{1},
	SerialNumber:          big.NewInt(1),
make: *** [style] Error 1
```

Signed-off-by: Ivan Babrou <ibobrik@gmail.com>