Append number to prevent duplicate question headers
Since we now have question storage, we can look at existing question headers and
append a number if there's a match for a question filed in the same minute.
- add body as a constructor parameter to QuestionPoster -- the class can't do
much without the body set, and this simplifies the code in that we don't need
to pass $body to various methods.
- adjust some method visibility (addSignature)
- Move permissions checks into a method to try to make submit() a little more readable