Use new fxml and css with main application

.gitignore

@@ -1,3 +1,4 @@
-doc
 coverage
+doc
+.jrubyfx_cache
 .yardoc

lib/launchpad/gui/application.rb

@@ -3,14 +3,16 @@
 module Launchpad
   # Main application which is only created once at launch.
   class Application < JRubyFX::Application
+    fxml_root 'lib/launchpad/gui/fxml'
+
     # Automatically called on {Application.launch}
     # @param [Java::JavafxStage::Stage] stage
     #   automatically provided when {.launch} is called.
     def start(stage)
-      stage.title = 'Launchpad'
-      stage.width = 800
-      stage.height = 600
-      stage.show
+      with(stage, title: 'Launchpad', width: 800, height: 600) do
+        fxml 'main.fxml'
+        show
+      end
     end
   end
 end

spec/lib/launchpad/gui/application_spec.rb

@@ -5,7 +5,7 @@
     let(:stage) { double 'stage' }
 
     before do
-      messages = [:title=, :width=, :height=, :show]
+      messages = [:title=, :width=, :height=, :fxml, :show]
       messages.each { |message| allow(stage).to receive message }
       subject.start stage
     end
@@ -14,6 +14,7 @@
       expect(stage).to have_received(:title=).with 'Launchpad'
       expect(stage).to have_received(:width=).with 800
       expect(stage).to have_received(:height=).with 600
+      expect(stage).to have_received(:fxml).with 'main.fxml'
       expect(stage).to have_received(:show)
     end