Api functionality related with the matches

Features:
url 'api/round/id'  retrieve the complete list of matches teams and scores
url 'api/match/id' allow to interact directly on a match
url 'api/score/id'  allow to updated the score
function set_winner determines the winner of the current set
function match_winner retrieve winner of the match (2 of 3 sets )

Pending features:
advance to the next round