WIP Hh accept answer

Currently the accept action in the answers list-item controller is not persisting the updated value for `accepted` to the DB.
I don't think we want this to be unique. It's always going to be true or false, and this will make it impossible to have more than one of each.

You could make a custom validator to validate that there is only one accepted answer per question.

I wonder if it would be better for a question to have one accepted_answer. This would make decorating a question with whether or not it has been answered yet easier and would prevent any possibility of having multiple accepted answers.