* Split bid_duration field into forward/reverse durations
* Update params.go
* Update params_test for forward/reverse bid durations
* Remove duplicated import
* Replace bid duration on place bids
* Fix reversed bid errors
* Update auctions test
* Update bidding test
* Update testutil suite to use default forward/reverse bid durations
* Fix missing ReverseBidDuration param field
* Check if auction is reversed on forward bid
* Add test for conversion to reverse auction that reaches maxbid
* Make proto fields backwards compatible
* Use ForwardBidDuration for debt bid
* Make copy of v16 auction types
this doesn't actually work but keeping it in history
* Disable migrations
* Update debt tests to use forward bid duration