Remove rsyslog containers from swift-hosts

* Setup rsyslog configuration on the storage nodes
* Removes the requirement for an 'lxc' VG on swift nodes
* Adjust environment to not start rsyslog containers
* Fix log names for error logs to ensure they are configured
* Fix the container setup plays to allow an empty list of containers
  for a host

Fixes: #522
Merge pull request #523 from andymcc/swift_rsyslog

Remove rsyslog containers from swift-hosts