The current set should be Emoji One.
I replaced many of the smilies by myself with the "default" apple ones:
http://emojipedia.org/apple/
For unicodes, I used the extracted ones from here: https://github.com/github/gemoji/tree/master/images/emoji/unicode
I am not quite sure if I will replace all of them, because for the rest I have to do this manually.
Haven't thought of a automatic replacement for now, so it may be possible in an easy way.
However I can give you my mixed set if it would help? It replaces the unicode pngs from the gemoji project, all of the smiley "faces" and some smaller things like the thumps up/down emoji or the monkey.
I am not quite sure if they are free to use, I see them on Whatsapp, Telegram, ... but I could not found any legal information about this. You may could ask for copyright information here http://www.apple.com/legal/contact/