Move app to separate class

spec/app_spec.cr

@@ -0,0 +1,7 @@
+require "./spec_helper"
+
+describe App do
+  it "should compile" do
+    app = App.new
+  end
+end

spec/spec_helper.cr

@@ -1,6 +1,7 @@
 require "spec"
 require "../src/game/**"
 require "../src/cli/**"
+require "../src/app"
 
 def create_map_2x2 : Game::Map
   map = Game::Map.new 2, 2