def unvote!(voteable)
      begin
        unvote(voteable)
        success = true
      rescue Exceptions::NotVotedError
        success = false
      end
      success
    end
def unvote!(voteable)
      begin
        unvote(voteable)
        success = true
      rescue Exceptions::NotVotedError
        success = false
      end
      success
    end
Clears an already done vote on a +voteable+, but doesn't raise an error if
 the voteable was not voted. It ignores the unvote then.