Moved all files under Assets into Resources

Move all files that are sitting outside of Resources into the Resources folder so they can be indexed at runtime (for example - the Tiled importer pulls in prefabs via the FindResources command).

In the future I think we want to move to a more component-centric style of folder structure:

````
/weapons/swords/sword1.prefab
/weapons/swords/sprites/sword1.sprite
/weapons/swords/scripts/swordAttackScript.cs
/weapons/swords/animations/sword1.anim
````

etc.