DummyGenerator: Add Sprockets manifest

Rails stopped creating sprockets files but we still use sprockets. And we need to manifest so that test apps
generated during specs do not fail with a sprockets error.

Author: tvdeyen

core/lib/generators/spree/dummy/dummy_generator.rb

@@ -61,6 +61,7 @@ def test_dummy_config
       template "rails/application.rb.tt", "#{dummy_path}/config/application.rb", force: true
       template "rails/routes.rb", "#{dummy_path}/config/routes.rb", force: true
       template "rails/test.rb", "#{dummy_path}/config/environments/test.rb", force: true
+      template "rails/manifest.js", "#{dummy_path}/app/assets/config/manifest.js", force: true
     end
 
     def test_dummy_inject_extension_requirements

core/lib/generators/spree/dummy/templates/rails/manifest.js

@@ -0,0 +1,3 @@
+//= link_tree ../images
+//= link_directory ../javascripts .js
+//= link_directory ../stylesheets .css