VMware: place instances under resource pool

Currently, all the instances are placed under the default/root resource pool in vCenter cluster.
This does not allow to manage resources specific for tenants [1].
This blueprint will group instances under specific resource pool on vCenter whose name
matches the tenant/project name. This will happen only when the administrator has
defined a resource pool on vCenter. Otherwise, instances would be grouped under the default/root
resource pool. Thus, the change is backward compatible and affects only new instances.
Also, there would be no change in user or tenant workflow.

This is a Telco requirement for managing resources in a multi-tenant scenario within vCenter cluster.

[1] http://tinyurl.com/o8p4q59