Slight UI change in gnome-games (aisleriot)

[Callum McKenzie <callum physics otago ac nz>]

With Aisleriot I had experimentally changed replaced the stock new button 
with the stock play button. Since this didn't improve anything and 
attracted complaints I have reverted the change. Hopefully this should 
affect no one since it should be swapping one stock item for another 
(hence no i18n issue) and I do the screenshots and the documentation 
(hence no docs issue). None-the-less I am dutifully reporting this as per 
the String and UI announcement period rules just in case.

 - Callum