Added Identical rule

had a problem with the Identical validator, when its validated through ajax it requires the value of the other form element and jquery validate does not send this.

I am aware that this: '[name="' . $validator->getToken() . '"]' will not work out when there are more elements with the same name on the page but its the best I can come up with for now.
Added unit test for identical rule
Now with comparing to get rules, silly me
Merge pull request #4 from Fraak/patch-1

Identical rule