Import/export without UUIDs

[diogotcorreia]

For some users, the added complexity of including UUIDs in the exported files (that are used in other tools for collaborative editing, for example) is not worth it, since they are not using duplicate keys.
It would be better to have an option to export these files without including UUIDs instead.

The import function should also support importing without UUIDs and have mechanisms in place to handle imports of translations that have duplicate keys.