Because some bugs of nemus occur in test-nodes, when use popen occur
"RuntimeError: Error from slave: 500 Unknown command", or when add
veth name option error. I write sample module my_net to mangae the net
ns.

my_net: use unshare to create net namespace, then use nsenter to enter
ns correpand to execute cmd like add device, set ip address... and
cotain some network demo for running tests.

re6st_wrap: wrap the deploy of re6st node, ease the creation of cert
file and run of the node

test_net contain the tests:
  - ping test: net segment(router), multi-net segment(demo),
	       test after a reboot
  - hmac test: test on demo

ping is like ping file in demo, a script to run multiping