Move from side1, side2 to match sides[].

Right now on BK matches are limited to 2 sides. To support more custom types of tourneys, we need to allow battle royale, teams, etc we should switch to matches having teams and teams being sorted by seed first, then by name. Essentially we transform the match_sides table from a side1, side2, table like now to a link table between teams and matches. So instead of match.sides.team1, we will now have match.teams[0].