Avoid keeping the resource mounted because of some failure
fix if syntax in unmounted-install-tweaks.sh
add test script to check syntax of all sh scripts in assets/

It is often hard to test these scripts, since they have to be run after the
end of a long process, we can do a quick check here to make sure that the
syntax is OK.
upgrade busybox to v1.22.1 to get a working readlink

readlink is needed by the ./stop-debian.sh logic for killing all processes
from the chroot.  I threw in chgrp for completeness, and removed the touch
flags since they are not used and cause the build to fail.
removing /system binding

chroot by default needs shell at /system/bin/sh,
the env variable SHELL changes it to /bin/sh which is default shell in debian
adding feature to start Debian installed in internal storage after Android booting completed

when Debian is installed in /data partition then it is available to boot after Android is booted, instead of waiting for sdcard mount
lower limit to free size for debian install

Prevent installation of debian if the free size is less than predefined variable named 'MinimumFreeSize'
moving to cdebootstrap v0.6.3 from v0.6.2
re-structuring install broadcast listener registration and unregistration.

The broadcast listeners were registered only in onResume(), and they were also
unregistration in onPause(), so InstallActivity would not get the broadcast
unless it was the current Activity
Specifically format commit's author date rather than transforming it for faketime.

closes #105
set version code/name based on time/date of most recent commit

This helps with the deterministic build process since every build should
always be based on the same date.  Also, force the timezone to UTC to
eliminate timezone differences.
automatically include version in release APKs

a nice little hack from here:
http://jeffreysambells.com/2013/02/14/build-your-android-apk-with-the-manifest-version-number
for ant build, run clock at 5% speed

This should help produce reproducible timestamps in the APK file.
remove .sh from script so shebang can be easily changed

These scripts need not be implemented in /bin/sh, that's just an
implementation detail that should be hidden.
remove ant.properties from git, it is not used at all

The make-release-build script also will copy ant.properties into place to
setup the release signing key.
only gpg-sign a release build if gpg is available with secret keys

This makes it easy for people to run this script to verify the official
release build matches their build.