Crash fix for a case where the EndCallback is not set and used
Merge pull request #209 from robUx4/endcallback_npe_fix

Crash fix for a case where the EndCallback is not set and used
Merge branch 'master' of https://github.com/koush/AndroidAsync

# By Steve Lhomme
# Via Koushik Dutta (1) and Steve Lhomme (1)
* 'master' of https://github.com/koush/AndroidAsync:
  Crash fix for a case where the EndCallback is not set and used