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.
Basically, with the QuestionActivity responsible for creating the answer, the answer dialog fragment doesn't need to know what the question is. Which nicely avoids a bunch of annoying callbacks in the fragment, which I have no nice way of handling errors from.