Add filesystem abstraction for NetBSD (#1267)
Add filesystem abstraction for NetBSD (#1267)

* Add fs abstraction file for NetBSD
* Add init function with verification that the unzip binary is
  available

Co-authored-by: Lawrence Hoffman <776051768b480c5db830eea0ed552695cc01198c@block-g.com>
luarocks/luarocks,keplerproject/luarocks,keplerproject/luarocks,keplerproject/luarocks,keplerproject/luarocks,luarocks/luarocks,luarocks/luarocks