add Lua lang

lua/spec/gilded_rose_spec.lua

@@ -0,0 +1,10 @@
+local Item = require("src/item")
+local GildedRose = require("src/gilded_rose")
+
+describe("Gilded Rose", function()
+  it("should foo", function()
+    local gilded_rose = GildedRose:new({ Item:new("foo", 0, 0) })
+    local items = gilded_rose:updateQuality()
+    assert.same("fixme", items[1].name)
+  end)
+end)