when the dipiece is send a signal for create new piece, then create a new piece
set the new game button to bold
set the cssAnimateTimeout to 300 milliseconds
don't use fade since it seems slower when popup the modal
set up the isPieceReady function to add and remove the class manually, b/c the angular createNewPiece is in the same digest loop, so it can't create the piece in different digest loop
separate the animation behind different class
add ngClass binding in the html
add variables in animation time
update the comment