Updates to make `task_update` behave more safely.

* By the looks of the existing `_extract_annotations_from_task` method, the serialized annotation format has changed since writing; this modification will support both the former and current serialization formats.
* The second problem is somewhat more subtle: say that you have a UDA-defined parameter on one computer, but also synchronize with another computer that does not have said UDA defined; in the second computer, having no idea of the original task's UDA, will interpret the UDA-defined parameter as the description.