Extract display into supervision tree.

test/options_test.exs

@@ -1,23 +1,8 @@
 defmodule OptionTest do
   use ExUnit.Case, async: true
 
-  test "has default options" do
-    Options.start([])
-    assert Options.clear_screen?
-  end
-
-  test "override clearing of screen" do
-    Options.start(["--no-clear-screen"])
-    refute Options.clear_screen?
-  end
-
   test "can target specifc koans" do
     Options.start(["--koan=Strings"])
     assert Options.initial_koan() == Strings
   end
-
-  test "ignores unknown options" do
-    Options.start(["--foo"])
-    assert Options.clear_screen?
-  end
 end