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`)

vendor/github.com/docker/docker/client/image_remove.go

@@ -0,0 +1,31 @@
+package client
+
+import (
+	"encoding/json"
+	"net/url"
+
+	"github.com/docker/docker/api/types"
+	"golang.org/x/net/context"
+)
+
+// ImageRemove removes an image from the docker host.
+func (cli *Client) ImageRemove(ctx context.Context, imageID string, options types.ImageRemoveOptions) ([]types.ImageDeleteResponseItem, error) {
+	query := url.Values{}
+
+	if options.Force {
+		query.Set("force", "1")
+	}
+	if !options.PruneChildren {
+		query.Set("noprune", "1")
+	}
+
+	resp, err := cli.delete(ctx, "/images/"+imageID, query, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	var dels []types.ImageDeleteResponseItem
+	err = json.NewDecoder(resp.body).Decode(&dels)
+	ensureReaderClosed(resp)
+	return dels, err
+}