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/go-connections/tlsconfig/certpool_go17.go

@@ -0,0 +1,21 @@
+// +build go1.7
+
+package tlsconfig
+
+import (
+	"crypto/x509"
+	"runtime"
+
+	"github.com/Sirupsen/logrus"
+)
+
+// SystemCertPool returns a copy of the system cert pool,
+// returns an error if failed to load or empty pool on windows.
+func SystemCertPool() (*x509.CertPool, error) {
+	certpool, err := x509.SystemCertPool()
+	if err != nil && runtime.GOOS == "windows" {
+		logrus.Infof("Unable to use system certificate pool: %v", err)
+		return x509.NewCertPool(), nil
+	}
+	return certpool, err
+}