This villager is called Mel. He can give you 2 diamond chestplates for 20 emeralds, 1 iron boots for 15 emeralds, 1 gold leggings for 17 emeralds, 2 leather caps for 14 emeralds & 1 leather cap for 7 emeralds.
[UPDATED VERSION RELEASED ON 26 NOVEMBER 2017!]
Both the old and new version can be found in the command box. :)