Credit offer feature request

https://wallet.bitshares.org/#/credit-offer

As a user, I would like to see a recent history of borrowing rates in a credit offer, just like smart coin's price feed data.

https://wallet.bitshares.org/#/asset/USD

Start at the credit-offer page linked in the issue, then compare it with the linked USD asset page and its smart coin price feed data. Determine how recent borrowing rates should be sourced and displayed; done means a credit offer shows a recent borrowing-rate history comparable to the existing price-feed history.

Written by the indexing model from the issue text.