Merge pull request #16 from jperedadnr/master

Added Clear Sans Font, and pop animation
Merge pull request #17 from jperedadnr/master

* Added Best Score, Clock and Pause
* Added resizable capabilities
Merge pull request #18 from jperedadnr/master

Added Board to handle the view of the game. GameManager takes care of the logic
Merge pull request #19 from jperedadnr/master

Fixed css styling
removed unused method
removed unused method
usage of Optional for study. And code format
Code formatting
* Added Grid class to hold the traverseGrid method
* Added Optional to Tile and GameManager to look for merging nullable tiles
* Provided default styling to grid