Added unit tests for both testing the functinality of the TenCrop and
its error messages. Due to the similarity of this method to FiveCrop the
test cases are similar to FiveCrop test cases.
Signed-off-by: Mahdi <mahdi.rahmani.hanzaki@huawei.com>

added error_msg function call in the main method

refactored the test and added visual representation of the results

Separated the two error cases into two different functions and used the
visualize function in util.py to plot the result of TenCrop.
Signed-off-by: Mahdi <mahdi.rahmani.hanzaki@huawei.com>

Added new test cases

Added new test cases including test case for checking the error message
when the size variable is not a positive integer, test case for
rectangle crop, test case for vertical flip setting, and testing for
similarity of the result of TenCrop for the same input data in different runs.
Signed-off-by: Mahdi <mahdi.rahmani.hanzaki@huawei.com>

changed visualize in test_five_crop

Changed the visualize function in test_five_crop to use the already
existing function in util.py
Signed-off-by: Mahdi <mahdi.rahmani.hanzaki@huawei.com>

made generate_golden variable global