Update Validator.php

Hi, I have added a strict flag as an argument since anyone who wishes a strict comparison shall have the option, and btw in_array without strict is sort of "useless" in most cases, IMHO.

heres why i say so.
http://php.net/manual/en/function.in-array.php#106319
Merge pull request #114 from cguroo/patch-1

Add optional "strict" check for "in" validator that uses "in_array()"