uninstall Lil' Debi if Terminal Emulator not installed first

It turns out that if Terminal Emulator is installed after Lil' Debi, then
Lil' Debi can't use Terminal Emulator's permission.  The only way I could
find to solve this is to uninstall Lil' Debi, make sure Terminal Emulator
is installed, then reinstall Lil' Debi.
implementing minimumFreeSizeTest function

This function tests whether the requested size for installation is greater
than MinimumFreeSize (250MB) else it will disable the install button and
change its text to 'Not enough space (< 250MB)'. The earlier Toast which does
this work is been removed.

fixes #117 https://github.com/guardianproject/lildebi/issues/117
restore image_path from the Image path EditText box

when we uncheck 'Install on Internal Storage' we have to replace image
path from Image path Edit text box, instead of default value
fix crash on resuming InstallActivity when using internal storage

If we resume InstallActivity keeping the Image size black we get NumberFormatException
Change NativeHelper.limitTo4GB after '4GB Image Limit' Setting changed
show error if the loopback image cannot be mounted during install
support SuperSU on older than Android 4.2/android-17

Android 4.2 introduced multi-user support and added some bizarre mount
hacks (i.e. /storage/emulated...). koush's Superuser supports them
transparently, but SuperSU requires that you call su differently in order
to support that mount weirdness.  It is doable to support SuperSU, but I'll
leave it at "patches welcome" since it is a proprietary app.
improve "Get Superuser" messages
test to check cyanogen BUILD to see if device is rooted or not

as latest cyanogen build does not explicit superuser application
check if Debian image is available after SDcard is unmounted

as some devices has multiple SDcards
install android-permissions as early as possible in the install process

This package sets up all the Android app users and permissions groups.  It
needs to be installed as early as possible to claim the uids for group
names like 'bluetooth' that also exist in Debian.
include script for automating comparisons of release APKs

This is useful for checking whether the build is reproducible.
make /debian/shell work for normal users too
don't set the hardware clock on shutdown, Android will take care of that
properly initialize image_path when "Internal Storage" is true
attempt to auto-detect existing internal install

This code tries to find an existing internal install, then uses that as the
default value when reading the actual pref.  This is useful for when the
app has been uninstalled and reinstalled, but the internal install is still
in place.
/debian/shell needs to also force the use of busybox's `id -u`

`id -u` must return only a single number, so busybox's id is included. This
makes /debian/shell use it when launching a login shell, so /etc/profile
can work properly.
add pretty Debian-style messages to stop-debian.sh