Re-think integration vendoring

- remove docker/docker from  Traefik vendor (unused)
- use `ignore` for all Traefik vendor in integration glide.
- defined only integration specific version of the dependencies.

integration/vendor/github.com/docker/go-connections/tlsconfig/config.go

@@ -46,23 +46,19 @@ var acceptedCBCCiphers = []uint16{
 // known weak algorithms removed.
 var DefaultServerAcceptedCiphers = append(clientCipherSuites, acceptedCBCCiphers...)
 
-// ServerDefault returns a secure-enough TLS configuration for the server TLS configuration.
-func ServerDefault() *tls.Config {
-	return &tls.Config{
-		// Avoid fallback to SSL protocols < TLS1.0
-		MinVersion:               tls.VersionTLS10,
-		PreferServerCipherSuites: true,
-		CipherSuites:             DefaultServerAcceptedCiphers,
-	}
+// ServerDefault is a secure-enough TLS configuration for the server TLS configuration.
+var ServerDefault = tls.Config{
+	// Avoid fallback to SSL protocols < TLS1.0
+	MinVersion:               tls.VersionTLS10,
+	PreferServerCipherSuites: true,
+	CipherSuites:             DefaultServerAcceptedCiphers,
 }
 
-// ClientDefault returns a secure-enough TLS configuration for the client TLS configuration.
-func ClientDefault() *tls.Config {
-	return &tls.Config{
-		// Prefer TLS1.2 as the client minimum
-		MinVersion:   tls.VersionTLS12,
-		CipherSuites: clientCipherSuites,
-	}
+// ClientDefault is a secure-enough TLS configuration for the client TLS configuration.
+var ClientDefault = tls.Config{
+	// Prefer TLS1.2 as the client minimum
+	MinVersion:   tls.VersionTLS12,
+	CipherSuites: clientCipherSuites,
 }
 
 // certPool returns an X.509 certificate pool from `caFile`, the certificate file.
@@ -82,7 +78,7 @@ func certPool(caFile string) (*x509.CertPool, error) {
 
 // Client returns a TLS configuration meant to be used by a client.
 func Client(options Options) (*tls.Config, error) {
-	tlsConfig := ClientDefault()
+	tlsConfig := ClientDefault
 	tlsConfig.InsecureSkipVerify = options.InsecureSkipVerify
 	if !options.InsecureSkipVerify && options.CAFile != "" {
 		CAs, err := certPool(options.CAFile)
@@ -100,12 +96,12 @@ func Client(options Options) (*tls.Config, error) {
 		tlsConfig.Certificates = []tls.Certificate{tlsCert}
 	}
 
-	return tlsConfig, nil
+	return &tlsConfig, nil
 }
 
 // Server returns a TLS configuration meant to be used by a server.
 func Server(options Options) (*tls.Config, error) {
-	tlsConfig := ServerDefault()
+	tlsConfig := ServerDefault
 	tlsConfig.ClientAuth = options.ClientAuth
 	tlsCert, err := tls.LoadX509KeyPair(options.CertFile, options.KeyFile)
 	if err != nil {
@@ -122,5 +118,5 @@ func Server(options Options) (*tls.Config, error) {
 		}
 		tlsConfig.ClientCAs = CAs
 	}
-	return tlsConfig, nil
+	return &tlsConfig, nil
 }