Q&A voting for questions and answers

As a User I'd like to be able to vote for question and answer so that I can both express my opinion on the quality of the question/answer and see the opinion of others

• Voting buttons and vote results should be visible for all forum visitors.
• It should be allowed to vote for question/answer only for registered users.
• New permission VOTE should be created.
• VOTE permission should be given to user's branch to allow voting.
• Once unregistered user wants to vote for question/answer and presses Upvote/Downvote button, the tooltip: “Voting is available for registered users only” should be shown for these buttons.
• It should not be possible for user to vote for question/answer which was created by him.
• If user had already made the vote but changed the mind afterward it should be allowed for user to change the vote to the opposite one:
  • Changing of the vote should be done by pressing the opposite button.
  • Ones the opposite button is pressed, the total votes sum should be changed accordingly (increase or decrease on 2 points). The buttons highlighting should be changed accordingly.
• User vote (up or down arrow) should be highlighting on UI, other arrow should be gray.
• Date of user vote should be stored in DB. If user change her vote - date should be updated (not created new one).
• Answers should be automatically sorted first by popularity (largest to fewest number of votes received) then by date (newest ones to oldest ones).