fix a problem occurring with slow animation and chow selection

the chow selection dialog was synchronous, it now returns the result
in a Deferred. Same of course for kong selection.

This commit also fixes this situation:

1. user says Chow
2. SelectChow dialog pops up when more than one chow combination is possible
3. previous animation ends, making animate() callback with current answer
4. but this answer is Chow, without a selected Chow. This is wrongly sent to server