adds vendor directory

vendors dependencies in standard `vendor` directory, managed by glide

vendor/github.com/mattn/go-gtk/example/expander/expander.go

@@ -0,0 +1,24 @@
+package main
+
+import (
+	"github.com/mattn/go-gtk/gtk"
+	"os"
+)
+
+func main() {
+	gtk.Init(&os.Args)
+	window := gtk.NewWindow(gtk.WINDOW_TOPLEVEL)
+	window.SetTitle("We love Expander")
+	window.Connect("destroy", gtk.MainQuit)
+
+	vbox := gtk.NewVBox(true, 0)
+	vbox.SetBorderWidth(5)
+	expander := gtk.NewExpander("dan the ...")
+	expander.Add(gtk.NewLabel("404 contents not found"))
+	vbox.PackStart(expander, false, false, 0)
+
+	window.Add(vbox)
+	window.ShowAll()
+
+	gtk.Main()
+}