refactor(auction.js) add a property to AuctionConstructor
refactor(*) rename AuctionConstructor to Auction
test(auction_spec) Auction can take a seller's price and update the 59105sellerPrice property
test(auction_spec) newBidder fucntion creates a new bidder and stores it on the Auction instance
test(auction_spec) newBidder gives each bidder a unique bidder_id
feat(auction.js) add newBidder function to the constructor
test(auction_spec) findHighestBidder function returns the highestBidder from  collection of bidders