Function registerAuctioneer(IBondAuctioneer auctioneer_)

1. Intended behavior.

   • Allows registering auctioneers_ , only callable by Guardian.

   • Stores into an array(could maybe be duplicated, but it doesn’t really matter)

   • Whitelists the auctioneer so that they can perform further actions (TBD)

   • only whitelisted callers can register new market

   • there isn’t a possibility of removing the address from the whitelist

   • make sure the auctioneer hasn’t been whitelisted before (!whitelisted[auctioneer])

2. Negative behavior.

   • Restriction on calls from untrusted users.