If we are already playing, ignore touches
Remove the TapToStart sing
Set the player in physics simulation. Give the player an upward impulse
Added GameObjectNode
Implemented collisionWithPlayer(GameObjectNode)
Implemented checkNodeRemoval (GameObjectNode)
Added StarNode
Implemented collisionWithPlayer (StarNode)
Create a StarNode given a certain position
Collision detection for the player node
Collision detection for the StarNode
Added SKPhysicsContactDelegate interface
Implementing the didBeginContact (collision detection)