Extract display into supervision tree.

lib/elixir_koans.ex

@@ -0,0 +1,15 @@
+defmodule ElixirKoans do
+  use Application
+  alias Options
+
+  def start(_type, _args) do
+    import Supervisor.Spec
+
+    children = [
+      worker(Display, [])
+    ]
+
+    opts = [strategy: :one_for_one, name: ElixirKoans.Supervisor]
+    Supervisor.start_link(children, opts)
+  end
+end