Revert "Switch to new vendor directory layout"

This reverts commit d5742209d3.

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

vendor/github.com/godbus/dbus/conn_darwin.go

@@ -1,21 +0,0 @@
-package dbus
-
-import (
-	"errors"
-	"os/exec"
-)
-
-func sessionBusPlatform() (*Conn, error) {
-	cmd := exec.Command("launchctl", "getenv", "DBUS_LAUNCHD_SESSION_BUS_SOCKET")
-	b, err := cmd.CombinedOutput()
-
-	if err != nil {
-		return nil, err
-	}
-
-	if len(b) == 0 {
-		return nil, errors.New("dbus: couldn't determine address of session bus")
-	}
-
-	return Dial("unix:path=" + string(b[:len(b)-1]))
-}