Current syntax:
lang_sync upload-base
lang_sync upload-translations

Options for new synax:
1) "lang_sync upload-dutch upload-de_DE" ("upload-" prefixed commands with either langname or isocode)
2) "lang_sync upload dutch upload de_DE" ("upload" command with parameter)
3) "lang_sync --lang dutch --lang de_DE upload-translations" (filter parameter, default="all languages")
4) Drop commands completely: "lang_sync --upload-base", "lang_sync --upload-translations", "lang_sync --upload dutch --upload=de_DE"