Retrive number of hosts from the cluster
Retrive number of hosts from the cluster

[#146469779](https://www.pivotaltracker.com/story/show/146469779)

Signed-off-by: Shoabe Shariff <6acd8ec3131907684119231b63383206d2a5a560@pivotal.io>

cloudfoundry-incubator/bosh-vsphere-cpi-release,cloudfoundry-incubator/bosh-vsphere-cpi-release,cloudfoundry-incubator/bosh-vsphere-cpi-release,cloudfoundry-incubator/bosh-vsphere-cpi-release,cloudfoundry-incubator/bosh-vsphere-cpi-release