Subject: sync'd assests file with APL-apk commit hash 8652941

Description:

1) preinstall.sh: conditional check to aakash.sh
2) aakash.sh: variable/paths renaming
3) MainActivity.java: download tar-ball from http://aakashlabs.org/builds/abt.tar.gz
4) README: minor changes to code line numbers for running in an emulator
5) README: latest apk available @ http://aakashlabs.org/builds/ABT.apk
6) removed TODO.rst (--> TODO.org)