Announce and record tournament winners

[twiceineverymoment]

Once the final match of an elimination tournament is marked as "completed" (the match where match_is_final = 2):

• Display the winner's name at the top of the bracket page
• Post a congratulations message to the activity feed
• Record a tourney win to the winner's rank table (2 new columns: rank_tourney_total and rank_tourney_wins)

[twiceineverymoment]

Test case:

• When the final match of a tournament is saved, confirm that an alert box pops up stating that the tournament is now over
• Visit the activity feed and confirm that a congratulations message to the tournament winner was posted
• Confirm that the winner has been given a tourney win in the rankings table