Make remote get/set of answers work in UI

I had to make pretty significant changes to the activities to make this work.
Due to all dataManager operations being necessarily asynchronous, and not working at all without a callback, it became cleaner to trigger creation of answer records in the question activity through a callback. To do so in the add answer fragment would have required several more levels of nested callbacks, and then to duplicate them again in the question activity.

On the bright side, besides being a lot of code, it does look kind of nice.