Adding additional properties to the stemcell for VMware hypervisor

This change adds some additional properties that can be defined in the stemcell manifest that are used when using VMware as a hypervisor under OpenStack per the discussion at https://groups.google.com/a/cloudfoundry.org/forum/?fromgroups#!topic/bosh-dev/IOipFP3Z9Rg.

Aaron Huber
Intel Corporation