Updated contributors username.

I changed my GitHub username and the old link doesn't work anymore.

README.md

@@ -13,7 +13,7 @@ Other notable contributors:
 
  - [TimPetricola](https://github.com/TimPetricola) added best score storage
  - [chrisprice](https://github.com/chrisprice) added custom code for swipe handling on mobile
- - [elektryk](https://github.com/elektryk) made swipes work on Windows Phone
+ - [marcingajda](https://github.com/marcingajda) made swipes work on Windows Phone
  - [mgarciaisaia](https://github.com/mgarciaisaia) added support for Android 2.3
 
 Many thanks to [rayhaanj](https://github.com/rayhaanj), [Mechazawa](https://github.com/Mechazawa), [grant](https://github.com/grant), [remram44](https://github.com/remram44) and [ghoullier](https://github.com/ghoullier) for the many other good contributions.