EVAL: paramaters as an array support

EVAL function overwrite on index.js (:1068) caused lost of support to handle parameters as an array ( [ param1, param2, ... , paramN ], callback), since assumes all of them will be passed on extended format ( param1, param2, ... , paramN, callback ).

I added a simple validation to make it compatible. Also, updated example code to probe and show how this two formats works fine now.