Added a modification for placing a game piece
Refactored newGame() to allow starting new games in the same engine. Note that this does not show that TicTacToe is able to undo; it only shows that reverting a RegisterEntity modification works properly, as everything is reverted back to the initial state. It does show that reverting a branch is properly propagated over the network.
refactored update() - it previously updated the New Game button once for every field, i.e. nine times. In addition, it now allows to start a new game when the current game is over
changed dependency to 0.1.0-SNAPSHOT, which fixes updating to previous states, i.e. undo, and added a button that lets the user undo moves.