Updated to current version 0.2.0

Changelog:

* [Feature]  Added user input for specifying amount of players and
turns to be played.
* [Clean-up]  Moved all user input checking from Monopoly to StartGame.
I'm using StartGame as the initialization class and keep the Monopoly
free from everything that isn't the game itself. (If you have any
other suggestions on that, Kieran, let me know.)
* [Clean-up]  Replaced Unit class with three separate classes
(subclasses of Tile) for each Unit type.
* [Clean-up]  As suggested, implemented updateMoney and updateProperty
methods.
* [Clean-up]  Changed Group.name field to Group.groupColor.
* [Testing]  Added test class feedback to every. single. class.
* [Bug]  Changed startGame() in StartGame to playGame(), the game
should run normally now.