french/verbiste: revert facultative NFS support

Make the NFS support optional isn't a consensusal move.

Related review: https://reviews.freebsd.org/D1230
french/verbiste: update PNG resource files

Unique verbiste.png file has been replaced by icons from
different size, from 16x16 to 512x512.

Related review: https://reviews.freebsd.org/D1230#inline-7709