Update libkv dependency

vendor/github.com/coreos/go-semver/example.go

@@ -0,0 +1,20 @@
+package main
+
+import (
+	"fmt"
+	"github.com/coreos/go-semver/semver"
+	"os"
+)
+
+func main() {
+	vA, err := semver.NewVersion(os.Args[1])
+	if err != nil {
+		fmt.Println(err.Error())
+	}
+	vB, err := semver.NewVersion(os.Args[2])
+	if err != nil {
+		fmt.Println(err.Error())
+	}
+
+	fmt.Printf("%s < %s == %t\n", vA, vB, vA.LessThan(*vB))
+}