Specify the player when triggering a move on a revealed card

Fixes #72, #493 
Please have a look at https://github.com/Cockatrice/Cockatrice/issues/72#issuecomment-68182612 for the full discussion.
I'm not so confident with this part of the code, so i'm unsure wether this patch could break something else.
Please hard-review this before committing.