make busybox build repeatable on my machine

Using `faketime` means the timestamps are forced to being the same, and
that is enough to make the builds bit-for-bit repeatable on my machine.
Hopefully it is enough for repeatable builds on other machine as well.
use faketime on release builds for deterministic builds

Running a program with faketime causes that program to recent a fixed time
based on the timestamp provided to faketime.  This ensures that the
timestamps in the files are always the same.

This gets the process to the point where the APK signature is transferrable
no matter who builds it.  This process does not produce an APK with the
same hash.
use special faketime timestamp format to freeze time

faketime needs to have a very specific timestamp format in order to freeze
time.  The time needs to be frozen so that the timestamps don't depend on
the speed of the machine that the build process is running on.  See `man
faketime` for more info on the "advanced timestamp format".  Also, force
time to UTC so its always the same on all machines.

https://lists.mayfirst.org/pipermail/guardian-dev/2014-April/003420.html
use faketime 'advanced timestamp format' to make it freeze time

I was using the write timestamp format, but I had forgotten the -f flag.
Adding it make faketime actually freeze time :-D

Thanks to Michael Rogers for spotting that.
force timezone to UTC for busybox

busybox includes a timestamp in its code, set in a C macro called both
BB_BT and AUTOCONF_TIMESTAMP.  BB_BT is set to AUTOCONF_TIMESTAMP in the
build flags.  AUTOCONF_TIMESTAMP is set in busybox/include/autoconf.h. This
timestamp includes the time zone, so make sure it is always UTC.
fix lintian errors
fix TypographyEllipsis lintian warning with script from fdroid

Thanks mvdan!
purge unused "run_command_hint" string
do not include commons-io-2.2-javadoc.jar in APK

Oops, this was unnecessarily doubling the size of the APK...