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_other.go

@@ -0,0 +1,16 @@
+// +build !go1.7
+
+package tlsconfig
+
+import (
+	"crypto/x509"
+
+	"github.com/Sirupsen/logrus"
+)
+
+// SystemCertPool returns an new empty cert pool,
+// accessing system cert pool is supported in go 1.7
+func SystemCertPool() (*x509.CertPool, error) {
+	logrus.Warn("Unable to use system certificate pool: requires building with go 1.7 or later")
+	return x509.NewCertPool(), nil
+}