Revert "Merge pull request #12 from autotest/provider-libs"

This reverts commit c6c5aa5719c1afd7d788b45b542c009cfb2c9590, reversing
changes made to 9ca076451044351e8c255465d33d0345f145993c.
Add virsh command testcase virsh_net_update

New files:
network/virsh_net_update.cfg
network/virsh_net_update.py

Signed-off-by: Guannan Ren <gren@redhat.com>