Merge Realtime initial bricks into master

Functionality added by this branch:

1. Setting up initial brick layout in subsequent clients.
2. Emitting brick kill messages from the client to the server.
3. Broadcasting brick kill messages from the server to all other clients.
4. Waiting for `bricksGroup` to be rendered before its bricks are killed as a result of an `'initial bricks'` message received from the server.
5. Waiting for `bricks` to be received from the server and for `bricksGroup` to be rendered before its bricks are killed as a result of a `'brick kill to other clients'` message received from the server.
6. Improved server `util.log` debugging messages.
7. Client `console.log` debugging messages when a brick is killed.