Episode.json refactoring ( lang-ISO.json )

episode.json provides the primary information about episodes.

In @imsesaok project peppercarrot_metadata episode.json was updated and I've added lang.json to make lang selection easier.

@Deevad provides an interesting ressource for langs we can't manage automatically : here

It should be nice to have all that information in only one file and automatically generated by the render farm.

Today episode.json is used by @imsesaok android reader app and my peppercarrot api

Related to #7 (closed)