@ashfurrow => Registration Flow

This takes someone new to Artsy to being registered and full set up. It also deals with logging in via Artsy u:p and updating the user to be registered and then presents you paddle + pin.

Attached to it is an experiemental version of web based bidding. There's complications around access tokens when using pin + number which basically makes it more effort than it's worth now. So I'll be switching it out in the next PR with the original native version and just going with that. Think I've got enough time to make all of it's required states.

*Note:* @1aurabrown this will not compile on yours anymore because you'll need to add some more CocoaPods keys. Run these

```
bundle exec pod keys set CardflightMerchantAccountStagingToken XXXX
bundle exec pod keys set CardflightMerchantAccountToken YYYY
```
I think 
> he only concern would be the model outliving the view controller that owns it.
Is fine.