More features:
.Added enemy prefab, with animation;
.Added sword animation when Player push button

 On branch master
 Changes to be committed:
	new file:   Assets/Prefabs/Enemy.prefab
	new file:   Assets/Prefabs/Enemy.prefab.meta
	modified:   Assets/Prefabs/Player.prefab
	modified:   Assets/Scenes/Scene.unity
	new file:   Assets/Scripts/EnemyScript.cs
	new file:   Assets/Scripts/EnemyScript.cs.meta
	modified:   Assets/Scripts/PlayerMobility.cs
	new file:   Assets/Scripts/SwordScript.cs
	new file:   Assets/Scripts/SwordScript.cs.meta
	new file:   Assets/Sprites/Bullet/AttackAnim.anim
	new file:   Assets/Sprites/Bullet/AttackAnim.anim.meta
	modified:   Assets/Sprites/Bullet/Bullet.png.meta
	new file:   Assets/Sprites/Spaceship/Enemy.anim
	new file:   Assets/Sprites/Spaceship/Enemy.anim.meta
	modified:   Assets/Sprites/Spaceship/Player.controller
	new file:   Assets/Sprites/Spaceship/Spaceship_4.controller
	new file:   Assets/Sprites/Spaceship/Spaceship_4.controller.meta