Separates matches into their own objects.

This allows for simultaneous matches, and makes it easier to track more
information about each match. As an example, this commit also adds a
message to be sent at the end of matches.

Works towards sbehrends/Live-WorldCup-Notification-for-Slack#1
Merge pull request #15 from Cyborg572/match_objects

Allow simultaneous matches, more tracking info and finished match notification