Remove ifdown op

Signed-off-by: Xuetao Guan <xuetao.guan@qq.com>
Force using python 2.7 for tashi

Signed-off-by: Xuetao Guan <xuetao.guan@qq.com>
Enable vnc for tashi_test instance

Signed-off-by: Xuetao Guan <xuetao.guan@qq.com>
Split tashi_stop to cm_stop and node_stop

Signed-off-by: Xuetao Guan <xuetao.guan@qq.com>
Change name node_ to nm_

Signed-off-by: Xuetao Guan <xuetao.guan@qq.com>
Update README

Signed-off-by: Xuetao Guan <xuetao.guan@qq.com>