Issue #3672: Reshare alert box is appearing twice

Fixes issue https://github.com/diaspora/diaspora/issues/3672

``PostViewerFeedback`` extends ``Feedback`` (which attach listeners on ``.reshare`` and ``.like``) but also has method ``initViews`` which creates a new ``FeedbackActions``, this one also extends ``Feedback``. 

``Feedback``'s ``initialize`` method calls ``initViews``, thus attaching its listeners twice.

I override on FeedbackActions ``initialize`` and ``events``