Improve Android file system read performance

Faster file system read performance on Android!

 * Raw filesystem read is approximately 40% faster
 * Game startup is approximately 12% faster
 * Uses Native AssetManager
 * ... Instead of custom unzip code
 * Also, because the code now does not rely on internal data structures used in `zip_support/ZipUtils.*`, it should be re-entrant.

Tests

 * Tested with https://github.com/folecr/SlideShowFSTest
 * Test results are average of 3 runs
 * Tested on Galaxy Nexus with Android 4.2.2

Test 1 https://github.com/folecr/SlideShowFSTest/tree/master/samples/Cpp/RawFSTest

 * Reads image data using CCFileUtils
 * Time taken to read data
    * Before : 297.5 millis
    * After : 125 millis
 * Approximately 40% faster

Test 2 https://github.com/folecr/SlideShowFSTest/tree/master/samples/Cpp/SlideShowFSTest

 * Creates and displays sprites from image data
 * Approximately 12% faster to display all sprites