@1aurabrown => Place Bids

Adds the networking required to send the POST to submit a bid. Then sits at the confirmation page. Removes the `BiddingWebViewController.swift` 

Also:
* fixes #145 
* fixes #137 
* partial fix for #144
Or this would even be more readable if you took the logic out of the methods that return an api signal kept it in the .then{} like
```
.then {
    return self.fulfillmentNav().user.bidder == nil ? self.createBidderForAuction(auctionID) : return RACSignal.empty()
}
```