add a tray, similar to those ones:

https://research.googleblog.com/2016/03/deep-learning-for-robots-learning-from.html

tune the VR demo a bit, to make it more user friendly.

data/tray/tray_textured2.mtl

@@ -0,0 +1,13 @@
+# Blender MTL File: 'tray_textured2.blend'
+# Material Count: 1
+
+newmtl None
+Ns 0.000000
+Ka 0.000000 0.000000 0.000000
+Kd 0.800000 0.800000 0.800000
+Ks 0.800000 0.800000 0.800000
+Ke 0.000000 0.000000 0.000000
+Ni 1.000000
+d 1.000000
+illum 2
+map_Kd tray.jpg