fix nova.conf permissions

file should be readable by nova, but only modifiable by root
Merge pull request #373 from mapleoin/user-group

fix nova.conf permissions
Ignore return value of open-iscsi start

the open-iscsi start command incorrectly returns "failed"
when there is no active sessions. It is quite normal that
there is no active session initially before the service
started..
Merge pull request #374 from dirkmueller/master

Ignore return value of open-iscsi start