Add some artist and maze simplified blocks to level editor

Artist (blocks still placeholder/WIP, waiting on art assets):

![image](https://cloud.githubusercontent.com/assets/206973/2836939/5df111da-d00a-11e3-82c3-0f1aa1c46c36.png)

Maze (blocks still WIP):

![image](https://cloud.githubusercontent.com/assets/206973/2836946/7793ec84-d00a-11e3-96ba-620e21fffdfc.png)