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.

#### Ready to merge checklist
- [ ] test(s) in test.js
- [ ] tests will fail without the PR, but succeed once applied
- [x] docs, if applicable
- [ ] merges cleanly
- [x] coding style (4-space indents, looks similar to other code)