Create `per-sale-fee` variant of the english_auction contract

[cpubot]

For the same reasons mentioned in #181 (tldr; we'd like to pay auction fees to each individual artist, the address of which will vary per auction), MinterPop would like a variant of an english auction contract in which fee_data is configurable per auction.

Make a variation of the english_auction contract which enables configuring fee_data per auction.