Use the old way of finding translations for OSX.

Use the old way of finding translations for OSX.

Many OSX users reported their clients being in Japanese, rather than
English, since 0.9.0, which turned out to be due to
QSystemLocale::query for QSystemLocal::UILanguages (internally done by
Qt if a QLocale is passed to QTranslator::load) returning 'en', rather
than the proper local form (e.g. 'en-US').
As 'en' has no translation, the second language got picked up, which
happened to be 'ja', which does have a translation.

Fixes #1233 (but reintroduces #1194 on OSX)