snippet for image_tranpsort subscriber

[stfuchs]

I haven't tested it with online_ros yet, but it builds locally. The node also doesn't do anything, because there is no camera publisher yet. It's basically just a template.

[davidmball]

Generally looks good. I'd suggest two things:

• add a second node to publish an image. You should be able to form a very simple (small) image with a for loop (ie grayscale or pattern) then send this
• remove the lifecycle. It distracts from what you are trying to show in the example itself.