Altered equalTo selector to find compare element in same form

[bramstroker]

equalTo validator will fail when I have 2 forms containing the target element with the same name.

i.e.

<form id="test1" name="test1">
    <input type="text" name="somefield" />
    <input type="text" name="somefield_again" />
</form>
<form id="test2" name="test2">
    <input type="text" name="somefield" />
    <input type="text" name="somefield_again" />
</form>

And my rules:

$('#test2').validate({
    rules : {
         somefield_again : {
             equalTo : "[name='somefield']"
         }
    }
});

This would fail in the second form, because somefield_again from form test2 will be compared to somefield of test1.

[bramstroker]

This PR seems a duplicate of #637. It is implemented in a much cleaner way in the other PR so I'll close this one.