Bookmark and poll plugins' custom notice forms now do AJAX submit, with the resulting...

Bookmark and poll plugins' custom notice forms now do AJAX submit, with the resulting notice appearing in the timeline.

FormNoticeXHR now is triggered on any form labeled with class 'ajax-notice', so those other than the traditional notice form should work as long as they handle the AJAX submission and return a properly formatted notice.

Things to watch out for:
* to determine whether the resulting notice should show on the current timeline, the JS code needs to be able to check the author and such. Keeping the existing vcard bits helps for this!
* the notice form submission stuff clears out inputs from your form -- test to make sure this behaves correctly
* error messages returned from the thingy _should_ come through, but this needs more testing for consistency
* while form components that aren't in a custom form should just be ignored, this should be tested more. (eg there's no location or attachment box for poll or bookmark plugins)
* NoticeListItem isn't currently reachable via autoloader -- touch NoticeList explicitly before calling into it for now.