Bug 1030972 - Import tasks from Bugzilla

@bobsilverberg @Osmose r?
I wonder if instead of keeping track of the number of criterion forms using an actual DOM element, you could create a selector that finds all of the criterion forms and then just return the count of those elements? This would save you from having to keep the number updated as you are doing at https://github.com/mozilla/oneanddone/pull/170/files#diff-d6e9936810ec6585d78cc77d41321946R18.