elementary: upgrade to 1.8.4

* Elementary 1.8.3 release
  http://sourceforge.net/mailarchive/message.php?msg_id=31826305
* Elementary 1.8.4 release
  http://sourceforge.net/mailarchive/message.php?msg_id=31895179


* introduce elementary-native for elm-prefs_cc and elementary_codegen
  binary

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>