adding jed1.x

I don't actually know that much about Jed format, but this was a quick-and-dirty way to make it work.  I imagine you'll want to clean it up.  There's one thing I'm not sure about, which I commented on below.
Yep, just tried right now.

I have this "Chapter : %d": \["Chapitre : %d", "Chapitres : %d"\] (English to French).

Same response returned, ```"Chapitres : %d"``` for all these cases :

  * ```t.ngettext('Chapter : %d', 'Chapters : %d', 3)``` //real one
  * ```t.ngettext('Chapter : %d', null, 3)```
  * ```t.ngettext('Chapter : %d', 'I HAVE NO IDEA WHAT I'M SAYING', 3)```
  * ```t.ngettext('Chapter : %d', function() {}, 3)```
  * ```t.ngettext('Chapter : %d', undefined, 3)```
  * ```t.ngettext('Chapter : %d', [], 3)```
  * ```t.ngettext('Chapter : %d', {}, 3)```
  * ```t.ngettext('Chapter : %d', this, 3)```

PS: just tried using Poeditor extractor when putting 

```t.sprintf(t.ngettext('Chapter : %d', null, this.props.story.chaptersCount), this.props.story.chaptersCount)```
instead of 
```t.sprintf(t.ngettext('Chapter : %d', 'Chapters : %d', this.props.story.chaptersCount), this.props.story.chaptersCount)```

and as I said, with null, poeditor didn't extract my po file. So, one good reason for the presence of the plural key is the ease of use of extract tools.