kernel code test: create a fake net_dev

This example is copied from
http://www.math.uaa.alaska.edu/~ssiewert/a320_code/EXAMPLES/Cooperstein-Drivers/s_24/lab1_network.c

And it works. Thanks a lot.
kernel code test: iterate on each netdev

This is also copied from

http://www.math.uaa.alaska.edu/~ssiewert/a320_code/EXAMPLES/Cooperstein-Drivers/s_25/lab1_devices.c
kernel code test: one example of container_of usage