Update traefik dependencies (docker/docker and related) (#1823)

Update traefik dependencies (docker/docker and related)

- Update dependencies
- Fix compilation problems
- Remove vdemeester/docker-events (in docker api now)
- Remove `integration/vendor`
- Use `testImport`
- update some deps.
- regenerate the lock from scratch (after a `glide cc`)

integration/vendor/github.com/libkermit/docker/image.go

@@ -1,40 +0,0 @@
-package docker
-
-import (
-	"fmt"
-	"io/ioutil"
-
-	"golang.org/x/net/context"
-
-	"github.com/docker/engine-api/client"
-	"github.com/docker/engine-api/types"
-)
-
-// Pull pulls the given reference (image)
-func (p *Project) Pull(ref string) error {
-	return p.ensureImageExists(ref, true)
-}
-
-func (p *Project) ensureImageExists(ref string, force bool) error {
-	if !force {
-		// Check if ref is already there
-		_, _, err := p.Client.ImageInspectWithRaw(context.Background(), ref, false)
-		if err != nil && !client.IsErrImageNotFound(err) {
-			return err
-		}
-		if err == nil {
-			return nil
-		}
-	}
-
-	// And pull it
-	responseBody, err := p.Client.ImagePull(context.Background(), ref, types.ImagePullOptions{})
-	if err != nil {
-		fmt.Printf("%v", err)
-		return err
-	}
-	defer responseBody.Close()
-
-	_, err = ioutil.ReadAll(responseBody)
-	return err
-}