Bug 1030876 - Add ability to clone tasks

Is there another way to know that we are dealing with a clone operation? Might a hidden form field be helpful for that? It just seems like we shouldn't have to use this test of the count of keywords to determine if it's a clone and therefore should be processed. I think the code would be simpler if it were left as it was before this, and just change the `if` statement to check for `'keywords' in self.changed_data` or `is_it_a_clone`.