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/sockets/unix_socket.go

@@ -1,30 +1,26 @@
-// +build linux freebsd solaris
+// +build !windows
 
 package sockets
 
 import (
-	"fmt"
 	"net"
 	"os"
-	"strconv"
 	"syscall"
-
-	"github.com/Sirupsen/logrus"
-	"github.com/opencontainers/runc/libcontainer/user"
 )
 
 // NewUnixSocket creates a unix socket with the specified path and group.
-func NewUnixSocket(path, group string) (net.Listener, error) {
+func NewUnixSocket(path string, gid int) (net.Listener, error) {
 	if err := syscall.Unlink(path); err != nil && !os.IsNotExist(err) {
 		return nil, err
 	}
 	mask := syscall.Umask(0777)
 	defer syscall.Umask(mask)
+
 	l, err := net.Listen("unix", path)
 	if err != nil {
 		return nil, err
 	}
-	if err := setSocketGroup(path, group); err != nil {
+	if err := os.Chown(path, 0, gid); err != nil {
 		l.Close()
 		return nil, err
 	}
@@ -34,47 +30,3 @@ func NewUnixSocket(path, group string) (net.Listener, error) {
 	}
 	return l, nil
 }
-
-func setSocketGroup(path, group string) error {
-	if group == "" {
-		return nil
-	}
-	if err := changeGroup(path, group); err != nil {
-		if group != "docker" {
-			return err
-		}
-		logrus.Debugf("Warning: could not change group %s to docker: %v", path, err)
-	}
-	return nil
-}
-
-func changeGroup(path string, nameOrGid string) error {
-	gid, err := lookupGidByName(nameOrGid)
-	if err != nil {
-		return err
-	}
-	logrus.Debugf("%s group found. gid: %d", nameOrGid, gid)
-	return os.Chown(path, 0, gid)
-}
-
-func lookupGidByName(nameOrGid string) (int, error) {
-	groupFile, err := user.GetGroupPath()
-	if err != nil {
-		return -1, err
-	}
-	groups, err := user.ParseGroupFileFilter(groupFile, func(g user.Group) bool {
-		return g.Name == nameOrGid || strconv.Itoa(g.Gid) == nameOrGid
-	})
-	if err != nil {
-		return -1, err
-	}
-	if groups != nil && len(groups) > 0 {
-		return groups[0].Gid, nil
-	}
-	gid, err := strconv.Atoi(nameOrGid)
-	if err == nil {
-		logrus.Warnf("Could not find GID %d", gid)
-		return gid, nil
-	}
-	return -1, fmt.Errorf("Group %s not found", nameOrGid)
-}