change activity status modal popup broken on Case Dashboard and Find Cases

Log time for this issue against: NYSS-6426 (http://dev.nysenate.gov/issues/6426)
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To recreate:

• create a case
• view case dashboard
• expand the case so that Activity listing is visible
• click linked "status" (changeActivityStatus jScript function) for one of the activities to open the change status dialog
  >> the Change Status select field is missing from the pop-up

Same problem from Find Cases

When changeActivityStatus is triggered from the Manage Case screen (CaseView.php), the field is present in the pop-up.

Currently the required select field is defined in CRM_Case_Form_CaseView::buildQuickForm
$this->add('select', 'activity_change_status', ts('New Status'), $activityStatus);

... but is not available in CRM_Case_Page_Dashboard

Lobo's suggestion is to reimplement the pop-up for all 3 contexts as as complete independent form (e.g. CRM_Case_Form_ActivityChangeStatus.