[contrib/lua] cjdlua utilily prints useful info.

depends:
apt-get install lua5.1 luarocks 
luarocks install bencode 
luarocks install dkjson
luarocks install luasocket
luarocks install sha2

Then in ./cjdns/contrib/lua  simply run either ./cjdlua or ./cjdlua l
![cjdlua](https://cloud.githubusercontent.com/assets/5460439/3579564/1af44a38-0bc3-11e4-9acb-4ada6c5af697.png)