* add 'bridge_type: linuxbridge' to tenks configuration to avoid
  dependency on OVS
* extend seed development environment testing to include overcloud
  provisioning and deployment
* remove seed hypervisor and seed VM environments. These are very
  stale, and largely replaced by a-universe-from-nothing. Add a link to
  that workshop on the same page

Change-Id: I9928e5912e6770bdcc1d5d0884d2f101c16ee6a9