Verification call_hooks(); method 

Fixing bug in CIUnit Component for acception in all Codeigniter 
versions (2 and 3.dev);
- In Codeigniter 2 is callable "_call_hook()"
- In Codeigniter 3 is callable "call_hook()"
Merge pull request #3 from willmendesneto/patch-1

Verification call_hooks(); method