Return translation as string

[raoulus]

Hi,

I wanna use this package in combination with https://github.com/nfl/react-helmet to dynamically set localized page titles. The <Helmet /> component only accepts strings... What do you think of exposing a utility function which returns just a string getTranslationAsString? I could imagine that this might useful also for other uses cases.

I can provide a pr, if you think this makes sense.