Issue WPI-AIM#216

Include the "environment" ADF file in the world file.

ambf_models/descriptions/world/raven_world.yaml

@@ -2,6 +2,7 @@ enclosure size: {length: 10.0, width: 10.0, height: 3.0}
 lights: [light1, light2]
 cameras: [camera1, camera2, camera3]
 namespace: /ambf/env/
+environment: "./checkered_floor.yaml"
 
 light1:
   location: {x: 0.0, y: 0.5, z: 2.5}
@@ -11,11 +12,12 @@ light1:
   cutoff angle: 0.7
 
 light2:
-  location: {x: 0.5, y: -1, z: 2.5}
+  name: light2
+  location: {x: 2, y: 2, z: 5}
   direction: {x: 0, y: 0, z: -1.0}
   spot exponent: 0.3
   shadow quality: 5
-  cutoff angle: 0.7
+  cutoff angle: 1.2
 
 light3:
   location: {x: 0.5, y: 0.0, z: -0.5}