Compatibility with AJAX Comments

Hello, Greg.

I found that recent update of my module AJAX Comments affects on Comment Notify functioning. The reason is that AJAX Comments modifies some of the comment form elements to allow safe and fast ajax submissions. One of this elements is 'nid', which converted from "value" to "hidden" FAPI element. Comment Notify threats 'nid' value only as "value" type and can't grab 'nid' parameter from the form, which completely disable comment notifications.

The solution is to check either "#value" is accessible, and if it's not, try to grab "#default_value" from the 'nid' element.

Please, take a look at the patch. Thanks.