gettext java support seems to be obsolete/unmaintained

[mikehearn]

Mikes-MacBook-Pro:app mike$ msgfmt --java i18n/cs.po -d client/src/main/resources/ -l cs -r lighthouse.locale.lighthouse
warning: [options] bootstrap class path not set in conjunction with -source 1.3
warning: [options] source value 1.3 is obsolete and will be removed in a future release
warning: [options] target value 1.1 is obsolete and will be removed in a future release
warning: [options] To suppress warnings about obsolete options, use -Xlint:-options.

I'm all for backwards compatibility but it seems javac and gettext will stop working at some point, it's requesting versions so old. We could translate to resource bundles but that doesn't support plural forms, however, AFAICT we don't use plural support anywhere (perhaps we should).

This is low priority. Probably gettext should be upgraded in some way to produce more modern source code.