Automatic Heritrix Version Detection

It would be best if NetarchiveSuite looked inside the heritrix bundle and took the Heritrix version from there. That way

1. We'd have fewer Constants to remember to update, and
2. The warc-files would still have the correct heritrix version even if we upgrade the bundler separately from the main software

Right now the only authoritative info on the heritrix version is the one in the heritrix stdout.