Add information on past data + ongoing info

[donjar]

Email from Wei:

It would be great to display for both the buyer and seller some on going information. Some basic information like these: Total number of registered buys and sellers, number of bids, number of asks, and total dollar amount or shares on the bids and asks. This will help give users senses of activities without revealing sensitive information.

We do have a function in services.py that is supposed to return these data, but currently it's just set to None. We should rework that as well as add more of these data.