Update CI build matrix & fix some lint

.travis.yml

@@ -1,8 +1,8 @@
 language: go
 
 go:
-  - 1.8.x
-  - 1.9.x
+  - 1.10.x
+  - 1.11.x
   - tip
 
 before_install:

transaction_test.go

@@ -175,7 +175,7 @@ func TestPAM_007(t *testing.T) {
 }
 
 func TestItem(t *testing.T) {
-	tx, err := StartFunc("passwd", "test", func(s Style, msg string) (string, error) {
+	tx, _ := StartFunc("passwd", "test", func(s Style, msg string) (string, error) {
 		return "", nil
 	})