Upgrade gin-gonic to latest master, fix compatibility issues

vendor/github.com/mattn/go-isatty/example_test.go

@@ -0,0 +1,18 @@
+package isatty_test
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/mattn/go-isatty"
+)
+
+func Example() {
+	if isatty.IsTerminal(os.Stdout.Fd()) {
+		fmt.Println("Is Terminal")
+	} else if isatty.IsCygwinTerminal(os.Stdout.Fd()) {
+		fmt.Println("Is Cygwin/MSYS2 Terminal")
+	} else {
+		fmt.Println("Is Not Terminal")
+	}
+}