dkjson: import from https://github.com/SeattleMeshnet/meshbox.git

Signed-off-by: Lars Gierth <larsg@systemli.org>
lua-sha2: import from https://github.com/SeattleMeshnet/meshbox.git

Signed-off-by: Lars Gierth <larsg@systemli.org>
lua-bencode: import from https://github.com/SeattleMeshnet/meshbox.git

Signed-off-by: Lars Gierth <larsg@systemli.org>