Add Level class
Change CharacterFactory's method "createCharacter"
Some code formatting
Add welcome screen and start menu
Merge branch 'quiz' into base

Conflicts:
	Zend/Zend.xcodeproj/project.pbxproj
	Zend/Zend/Character.h
	Zend/Zend/Character.m
	Zend/Zend/FatZombie.m
	Zend/Zend/GameScene.h
	Zend/Zend/GameScene.m
	Zend/Zend/Human.m
	Zend/Zend/Level.h
	Zend/Zend/Level.m
	Zend/Zend/Levels/Level0/platforms.json
	Zend/Zend/Levels/Level0/zombies.json
	Zend/Zend/Platform.h
	Zend/Zend/Platform.m
	Zend/Zend/PlatformFactory.h
	Zend/Zend/PlayerControl.h
	Zend/Zend/PlayerControl.m
	Zend/Zend/SkinnyZombie.m
merge branches base and quiz