Filemeta json v12

Filestore/Filelog metadata output to JSON.

Worked on feedback given after a review from Victor. Hope all issues were addressed.
I think this function could be cleaned up. Perhaps we can move the json_t objects into the LogFilestoreLogThread and move all the code that deals with it into it's own functions. The #ifdef HAVE_LIBJANSSON can then also be moved into those functions. That would make the main logic much easier to follow.