Add deal filter that only shows hands where the player is the dealer

[fkautz]

When a player is learning opening bids, it would be good to show only bids where they make the first choice as dealer.

[eseidel]

Seems like a very valid request and simple to implement.

This is where the deal selector view is implemented:
https://github.com/eseidel/saycbridge/blob/master/dist/gae/scripts/new_bidder.coffee#L32
This is where the actual filtering happens:
https://github.com/eseidel/saycbridge/blob/master/dist/gae/scripts/new_bidder.coffee#L257

Should be easy to just select for hands where all bidders prior to south have non-rule-of-twenty hands and south does.