Added Spawn and Kill methods for Character

Added Spawn and Kill methods for the Character class.
Added TK2D plugin for UI.
Added Health to Character

Reaching an health of 0, kills the character.
Added character Attack behaviour
Added Generic Blue and Red Knights
Improved character movement.

Removed slip movement.
Began Enemy prefab creation
Basic Enemy damaging behaviour

Created GameManager that tracks down the player and enemies in the game.
Created EnemyManager that works as a pool of enemies.