Allow deployment of VMs from templates in vSphere

This commit allows a 'vcloud' vmrun option, which will provision new
VMs from templates and place them in the specified folder and resource
pool.

A usage example for running Puppet acceptance tests would be:

  ./systest.rb \
    --vmrun vcloud \
    --config config/nodes/vcloud-test.cfg \
    --puppet origin/master \
    --facter origin/master \
    --hiera origin/master \
    --type git \
    --ntp \
    --root-keys \
    --xml \
    --pkg-repo \
    --debug \
    --tests acceptance-tests/tests \
    --helper acceptance-tests/lib/helper.rb \
    --keyfile="${HOME}/.ssh/id_rsa-old.private"

The referenced config/nodes/vclud-test.cfg file would look like:

  HOSTS:
    vcloud-master:
      roles:
        - master
        - database
        - agent
      template: wheezy-64
      platform: debian-7-amd64
    vcloud-agent:
      roles:
        - agent
      template: wheezy-64
      platform: debian-7-amd64
  CONFIG:
    nfs_server: none
    consoleport: 443
    datastore: instance0
    folder: Delivery/Quality Assurance/Staging/Dynamic
    resourcepool: delivery/Quality Assurance/Staging/Dynamic