Basic Spider Tank
work on #10
- Creates a simple spider tank that just has one canon that tracks the player and shoots constantly.
- Creates a prefab for the spider tank.
- Makes Weapon.IsOnCoolDown into a property.
- Removed Weapon.Init() and replaced it with Unity's Start() lifecycle method.
- Made _lives and _health in HealthSystem serialize in editor.
Merge branch 'master' into basic_boss

Conflicts:
	Assets/Scripts/WeaponSystem.cs
Collision With Scenery
closes #18
- Turns out scenery collision already works just fin (thanks to Adam for setting things up well!)
- Sets the default target on the weapon prefabs to just be "Scenery".
- Has the player weapons add "Enemy" to the list of targets on initialization.
Player Moves Via Rigidbody
work on #10
- Player is no longer kinematic, and is now moved via its rigidbody instead of its transform.
Merge pull request #20 from ModSquadWorkshop/basic_boss

Basic boss