ThreadPool Demo

Demo of burst capturing images with camera API using CameraPreview.
The app captures the Camera Preview on a background handler thread.
It then performs the following actions in a threadpool.

* Converted from YUV `byte[]` to RGB `int[]`.
* Converted from RGB `int[]` to `Bitmap`.
* Bitmap is rotated if needed to fix orientation.
* A Thumbnail size Bitmap is made for displaying.
* Full size bitmap is written to disk as a Jpeg.
* JPEG image is uploaded to a server (mock upload, does not really upload anything).

Source code for the app available at: https://github.com/alphamu/ThreadPoolWithCameraPreview
Write-up on the code available at: https://medium.com/@ali.muzaffar/using-concurrency-and-speed-and-performance-on-android-d00ab4c5c8e3