Add bid history for each post

![image](https://cloud.githubusercontent.com/assets/8669803/5032963/10621f74-6b30-11e4-9fc2-f6dae66ac230.png)

Unused method argument - `hash`. If it's necessary, use `_` or `_hash` as an argument name to indicate that it won't be used. You can also write as `update(*)` if you want the method to accept any arguments but don't care about them.