Allow to define a fallback value in Trans for cases not getting a translation

[jamuhl]

Details: #462

[brodeynewman]

We use this project at work and we think it would be cool to be able to pass a prop into the Trans component as the fallback value. Is this what you're thinking?

If so, i'd like to go ahead and knock this out.

[jamuhl]

@brodeynewman you're aware that its about this case: #462 (comment) -> empty node, no translation found

the inner content of the node acts as fallback already and is also used as default value for save missing.

[jamuhl]

or just apply https://github.com/i18next/react-i18next/pull/462/files#diff-e2b8d52a3ffb2c5b61049216c69ff761R108 should not be to harmful adding that on major v9 as final

[jamuhl]

@brodeynewman or props defaults -> https://github.com/i18next/react-i18next/blob/master/test/trans.render.spec.js#L356

[jamuhl]

published in react-i18next@9.0.0

allow defining transEmptyNodeValue in i18next.options.react to set a default fallback value