Remove usage of pkg sockets and tlsconfig.

- Use the ones provided by docker/go-connections, they are a drop in replacement.
- Remove pkg/sockets from docker.
- Keep pkg/tlsconfig because libnetwork still needs it and there is a
  circular dependency issue.

Signed-off-by: David Calavera <david.calavera@gmail.com>

plugins/client.go

@@ -11,8 +11,8 @@ import (
 	"time"
 
 	"github.com/Sirupsen/logrus"
-	"github.com/docker/docker/pkg/sockets"
-	"github.com/docker/docker/pkg/tlsconfig"
+	"github.com/docker/go-connections/sockets"
+	"github.com/docker/go-connections/tlsconfig"
 )
 
 const (

plugins/client_test.go

@@ -8,7 +8,7 @@ import (
 	"testing"
 	"time"
 
-	"github.com/docker/docker/pkg/tlsconfig"
+	"github.com/docker/go-connections/tlsconfig"
 )
 
 var (

plugins/plugins.go

@@ -28,7 +28,7 @@ import (
 	"time"
 
 	"github.com/Sirupsen/logrus"
-	"github.com/docker/docker/pkg/tlsconfig"
+	"github.com/docker/go-connections/tlsconfig"
 )
 
 var (