iscsi: Don't override selinux settings

The Iscsi object would "blindly" run "setenforce 0", do some initialization, and then run "setenforce 1" after.  If a host was already set in "Permissive", then this would place it back to "Enforcing".  Instead, add a check if the host is enforcing first, then set it permissive, do the initialization, and only if we had set it to Permissive do we reset it back to Enforcing.

Also cleaned up a couple of error messages in the Iscsi object