1316 plus a few more fixes on update_language_packs

OK, each commit here fixes something:
1. Use save_as_mofile for churning out mo files. Way faster and less errors than compilemessages.
2. Apparently the `--no-kalite-trans` option had the opposite effect, meaning that KA Lite translations only get downloaded when it's specified!
3. At the same time, KA Lite translations aren't really processed since the filtering process doesn't return them. Fixed.
4. UTF-8 now the default encoding for all strings. BOOM!