BibFormat: recjson update using BibReformat

* Adds `recjson` to the list of available formats that BibReformat
  could use. (closes #1708)

Signed-off-by: Esteban J. G. Gabancho <esteban.gabancho@gmail.com>
It is a bit weird to have one format in uppercase, one in lowercase.  Could they use the same case?