Add back _vendor directory and remove the rename to .es6

Rakefile

@@ -16,6 +16,8 @@ namespace :assets do
     sh 'cp -R bower_components/foundation-sites/scss/* vendor/assets/scss/'
     sh 'cp -R bower_components/foundation-sites/scss/settings/_settings.scss lib/generators/foundation/templates'
     sh 'cp -R bower_components/motion-ui/src/* vendor/assets/scss/motion-ui'
+    # NOTE: This is a temporary dependency management solution introduced in 6.3, will probably be removed in 6.4
+    sh 'cp -R bower_components/foundation-sites/_vendor/* vendor/assets/_vendor/'
 
     js_files = Dir['vendor/assets/js/*.js'].sort
     # Move foundation.core.js to beginning of js_files
@@ -25,10 +27,6 @@ namespace :assets do
     manifest = js_files.map { |file| "//= require #{File.basename(file)}" }.join("\n")
     File.write('vendor/assets/js/foundation.js', manifest)
 
-    Dir['vendor/assets/js/*.js'].each do |file|
-      sh "mv #{file} #{file}.es6"
-    end
-
     puts "\n*********************\n** ASSETS UPDATED! **\n*********************\n"
   end
 

vendor/assets/_vendor/normalize-scss/sass/_normalize.scss

@@ -0,0 +1,3 @@
+@import 'normalize/variables';
+@import 'normalize/vertical-rhythm';
+@import 'normalize/normalize-mixin';

vendor/assets/_vendor/normalize-scss/sass/normalize/_import-now.scss

@@ -0,0 +1,11 @@
+// Import Now
+//
+// If you import this module directly, it will immediately output all the CSS
+// needed to normalize default HTML elements across all browsers.
+//
+// ```
+// @import "normalize/import-now";
+// ```
+
+@import '../normalize';
+@include normalize();