Support for fallback to default language.

[stephenkopylov]

Please add support for fallback to default language.
In past it have worked, but now you see key name in the languages without translation.

[rubyluk]

@stephenkopylov Hello, thank you for reporting an issue. Can you email to support@oneskyapp.com with these information for better follow up?

1. your account email
2. the project id where this issue is found
3. filename ( if applicable )