Recognize the trash bag inside the bin

[robertocaiwu]

We need to recognize the trash bag inside the bin so that Lucy can pick it.

Context

This is needed for the Take out the garbage [see #110] task. Once the bin has been detected, we need to recognize the trash bag in order to pick it. The rulebook specifies that the trash bag is of a different color than the bin, so it should be possible to achieve this.