Improve how we store the outcome of the game

[Debilski]

We currently store the outcome of the game in two variables: gamestate['gameover'] and gamestate['whowins']. With gamestate['whowins'] == 2 signifying a draw. This is somewhat messy and cannot account for additional states. Most importantly, fixing #778 will introduce an additional state: ‘Could not start game’, which for example occurs when either one of the players could not connect. These games should not be counted as a winning condition for the non-failing team, so it makes sense to tell the CI or tournament to either ignore or attempt a replay.

[Debilski]

See pelita/viewer.py::ResultPrinter for how the current logic is being used.