Vendor all dependencies

Uses godep to vendor dependencies. Godeps is not necessary during build,
golang's new vendor support is used instead.

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

@@ -0,0 +1,21 @@
+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]))
+}