add build metadata to jar file to aid reproducible builds

This moves jar creation to `ant release`.

To provide build security, it should be possible for anyone to run the
build process and end up with the same result as Zetetic.  To aid that
process, this adds metadata to the release jar that specifies which
versions of Java, Android SDK, and Android NDK were used to build the
official release.
use faketime, if available, to set the build time based on the git commit

If the `faketime` utility is available, use it to fix the time of the build
based on the time of the current git commit.  This makes the build process
reproducible since anyone who builds it from git will end up with a build
that has the same exact timestamps.

You can get faketime from various package systems:
 apt-get install faketime
 brew install faketime
 port install libfaketime