Add option to invoke custom function when bid was created

[janisgitendorfs]

Linked: https://github.com/heroiclabs/hiro/pull/67

Case example When creating a game I would like to have option to hook into "before bid created" and "on successful bid". This way I am able to create validation if player have enough "bid tokens" and upon successful bid I can extract them allowing limited amount of bids placed by single player.

[novabyte]

@janisgitendorfs Why not make "bid tokens" into a currency which becomes part of the auction exchange of value? Can you describe more about how/when the player acquires "bid tokens"?

[janisgitendorfs]

@novabyte The idea would be to introduce flexibility on what it is used. In my mentioned scenario it would be great to use energy system and remove player energy when he bids on specific item, recharge and he can bid again.