NEW FEATURES

Vault Support

• Vault support added. You can enable economy by setting enableEconomy to true. This requires Vault and an compatible Economy plugin.
• You can replace the <item stack> value in the trades.config with: money: <double>
• I've made it so that money acts like regular items for trading.
• If you set enablePhysicalCurrency to true, then you can pickup money from the trade UI just like a normal item. The money can be deposited into your account at any time by pressing the DROP (default set to Q) key while hovering over the money item in your inventory.

Automatic Custom Trade Refreshing

• CustomTrades are now refreshed based on their unique key. That means that if you make a change to a custom key in the config, it will be reflected on all villagers that have that custom trade in the game.
• Note that and villagers that have custom trades before this update will not have their custom trades refreshed (they will be considered vanilla trades for refresh purposes).

Disable Vanilla Trades for Certain Professions

• If you only want to disable trades for certain professions you can choose which ones setting a list of disabled professions in the the disableVanillaTradesForProfessions field of the config.yml. Note that disableVanillaTrades must be set to false for this to work.

Checkout the README.md for more information.
This is the updated config.yml with the new options added.
And finally, this is the updated trades.yml with a lot more examples including using the new <money> option.