Fix few vet errors.

There are quite a few 'composite literal uses unkeyed fields' errors that I have kept out of this patch.
And there's a couple where vet just seems confused. These are the easiest ones.

pkg/client/clientcmd/provided_flags.go

@@ -96,5 +96,5 @@ func (flag *BoolFlag) Provided() bool {
 }
 
 func (flag *BoolFlag) String() string {
-	return fmt.Sprintf("%s", flag.Value)
+	return fmt.Sprintf("%t", flag.Value)
 }

pkg/client/request_test.go

@@ -393,7 +393,7 @@ func TestRequestWatch(t *testing.T) {
 		if testCase.Empty {
 			_, ok := <-watch.ResultChan()
 			if ok {
-				t.Errorf("%d: expected the watch to be empty: %#v", watch)
+				t.Errorf("%d: expected the watch to be empty: %#v", i, watch)
 			}
 		}
 	}