Duniter uses a buggy version of TweetNaCl

Duniter use C binding of TweetNaCl version 20130719, this version is buggy : http://seb.dbzteam.org/blog/2014/04/28/tweetnacl_arithmetic_bug.html#fnref:1

link to https://git.duniter.org/nodes/rust/duniter-rs/issues/183