Ignore errors from server console retrieval
Ignore errors from server console retrieval

Server console is used to get errors that may occur
during server boot. Those errors are used to give hints
on critical failures inside VM.

However it should not be critical not to get server console.

Change-Id: Ibf13111a85b8967475dda710830acb212c7d6796
Closes-Bug: #1800158

openstack/shaker,openstack/shaker,stackforge/shaker,stackforge/shaker,openstack/shaker