Canfield-Staging -> production

- Updated libgdx to version 1.0.0, which was released on April 20. This was required for the game lobby, and provides us with bug fixes and potential performance improvements.
- Created the multiplayer lobby screen:
    - Fully integrated with the lwjgl window: No more Swing window hiding behind the game window.
    - Players can message each other before the game starts
    - Server player can start the game by clicking a button
    - Countdown is integrated into the game lobby
    - This provides an example of how other screens could be integrated directly into the window: inherit from the abstract Screen class, and then pass that into graphics.draw
- Various minor fixes & typo corrections; more unit tests; updates to network integration tests to include the lobby screen