Fix imwrite parameters in obj_detect.py.

The location of the file path and image matrix had been accidentally
swapped.
Add example 6 test images.
Add test method for example 6 images.

It is located in the main method of obj_baxter.py.
Add example 6 test results.

Result images have "_segment" or "_roi" suffixes. The results strongly
indicate that the Baxter arm should be covered in a bright color like
red, to make subtracting it easier.