Release v6.4.3.0

### Major changes:
* Upgrade to Foundation `v6.4.3` (#254, @chrisfinne)
* Add Autoprefixer (#255, @bassjobsen)

### Bug fixes:
* Fix issue with smoothScroll import order (#236 @MicahBrown)
* Add missing SCSS components to template (#237 @patricklindsay)
* Prevent Sass depreciation (#252, @michsch)

### Cleaning:
* Remove old Foundation files (#251 @jessedoyle)

### See also:
* Foundation 6.4.3 release notes:
  https://github.com/zurb/foundation-sites/releases/tag/v6.4.3
* Foundation 6.4.2 release notes:
  https://github.com/zurb/foundation-sites/releases/tag/v6.4.2

lib/foundation/rails/version.rb

@@ -1,5 +1,5 @@
 module Foundation
   module Rails
-    VERSION = "6.4.3"
+    VERSION = "6.4.3.0"
   end
 end