compressed images on system partition

Change-Id: I43c8c331883b5b381fb0f133fff448f3a57d0fe5
Bug: 36446542
Test: Manual
Test: Create a stub and a compressed application; put on the /system partition
Test: Restart the system and see that it decompresses the full application onto the /data partition
Test: Restart again and see that we skip decompression
Test: Create an invalid compressed application [eg. empty file]
Test: Restart the system and see that the stub is disabled
Test: Restart again and see that we skip decompression