Fix android tutorial 3 second picture taken bug

Fix bug crash on second picture taken …
If the GC is not called, the onPictureTaken is never called. 
I found the solution on this thread: http://stackoverflow.com/questions/7258473/problem-with-taking-pictures-using-the-android-camera

Removed useless double jpeg compression
Cleaner callback

Reported on : http://code.opencv.org/issues/2961