Workaround for Android bug 10515463 on pre-4.4 devices

Just to add a more meaningful description to code change in Android Application subclasses. There is a confirmed bug in all pre-4.4 Android devices, which occurs rarely but could be very annoying to application developer. The reason for a bug is a racing condition in creating app private directory on first launch; Android Open Source project team member has suggested to try the Context.getFilesDir() method again after first one failed with a "null" return value.

There is no impact on runtime performance as figuring out the private directory location and creation of necessary files is done only once; subsequent calls get the internally cached location (path).

See pull request #1313 for previous discussion of this topic.