Update Ardent.php

Users of laravel 4.1 branch will get an error when the validator fires.

Due to the commit 5a1829f7658a5cf752b97c354fa89386ee60d5dc made to 4.1 framework branch in which hasSessionStore() method has been removed.
Merge pull request #154 from shrikantmeena/patch-1

Request::hasSessionStore() has been removed from Laravel.