Finally remove our copy of "archive/tar" now that Go 1.4 is the minimum!

IT'S ABOUT TIME. 🎉

Signed-off-by: Andrew "Tianon" Page <admwiggin@gmail.com>
Upstream-commit: 576985a1dcd76a9af2c5c483e6f12035a1f47b96
Component: engine

components/engine/integration-cli/docker_cli_push_test.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"archive/tar"
 	"fmt"
 	"io/ioutil"
 	"os"
@@ -8,7 +9,6 @@ import (
 	"strings"
 	"time"
 
-	"github.com/docker/docker/vendor/src/code.google.com/p/go/src/pkg/archive/tar"
 	"github.com/go-check/check"
 )