Update for novaclient 2.18

Regenerate ch_cli_nova_commands.xml with python-novaclient 2.18.0
release.

Closes-Bug: #1292259
Closes-Bug: #1315323
Closes-Bug: #1318734
Change-Id: Iba8018d571b1de6196b03975e4ff2c52f3ea3830
Merge "Update for novaclient 2.18"