Auction fee chat notification/change to percentage

[Shybella]

Auction fee should be changed from flat fee to percentage fee.

Ex: Diamonds * 64 sold for 1000 lets subtract 5% from 1000.
This should charge the player 50 if the fee-rate-percentage is 0.05in the config.
In addition, fees should be sent to a virtual eco account. This can be a configurable option.

Auction fee chat notification should be posted to the player if item is sold.

Ex: You have been charged 50 (5%) for auctioning your item
This should display the amount charged, not the percentage charged.
Item should display the item in chat.