Updated GameHelper.java to work with the latest GMSCore
Merge pull request #77 from hak/master

Updated GameHelper.java to work with the latest GMSCore
Merge branch 'master' of https://github.com/playgameservices/android-samples

# By Hak Matsuda
# Via Hak Matsuda (1) and Todd Kerpelman (1)
* 'master' of https://github.com/playgameservices/android-samples:
  Updated GameHelper.java to work with the latest GMSCore