[RFC] Provide failing test case for king moves

Failing test case for the bug that @BiviaBen explains in #16 

The following test case fails in ``master`` and passes in the branch ``BPC/benevolent-king-fix``

Ignore travis-ci for master based PRs. Use ``phpunit tests/ChessGameTest`` to test. 

Notice that testKingValidMovesMakingMoves is the test that fails. TestKingValidMovesWithMoveSAN passes. 

//cc @jseverson @lackovic10