Enlarge snake and food

	*snake and food edges are kind of blurry
	*snake can't go backwards but can go partially on top of itself
	may have to change that.
	*snake must go exactly on top of food to eat it -- I think I'm
	okay with that UX though
Add multiplayer button and firebase script.

	* Still figuring out how to open a connection with firebase
	while playing the game
	* also how I want to instantiate a second snake.
Change speed and food to reasonable size
Merge pull request #5 from mathildemouw/MVP_foodtarget

Mvp foodtarget