Added support to configure cloud using ovs+vlan

To configure neutron using openvswitch with VLAN support set environment
variables `networkingplugin` to `openvswitch` and `networkingmode` to
`vlan`.
I think you mean e.g. here instead of i.e. (i.e. is used as an explanation, e.g. for examples :)) http://en.wiktionary.org/wiki/i.e.#Usage_notes