Refactor index.html and import Grid module. Add grid directive into main.html
Fix app.js syntax error.
Inject GridManager.
Create unit test for TileModel within Grid module.
Create unit test for GridManager within Grid module.
Implement GridManager service and pass unit test.
Update test for generateEmptyGameBoard.
Update generateEmptyGameBoard method in Grid module and pass new test.
Refactor TileModel. Instead of storing x, y, we store coordinate object which contains x and y. Pass test.
Update unit test for generateEmptyGameBoard. Now it requires that method to initialize both grid and tiles.
Refactor generateEmptyGameBoard method. It will initialize both grid and tiles. Delete initTiles method.
Create unit test for availableCells method.
Create availableCells method. Pass test.
Create unit test for removeTile method.
Create removeTile method. Pass test.
Create initGameBoard method.