Basic splash page set up

Just getting the bare minimum styles and templates created and rendering
properly to have a simple splash going.

config/packages/sensio_framework_extra.yaml

@@ -0,0 +1,3 @@
+sensio_framework_extra:
+    router:
+        annotations: false

config/packages/twig.yaml

@@ -0,0 +1,6 @@
+twig:
+    default_path: '%kernel.project_dir%/templates'
+
+when@test:
+    twig:
+        strict_variables: true