Add dependency on vcloud-director 1.8.2-alpha-cloudsoft.6

- Because jclouds 1.8.1 release has bugs, and vcloud-director is
  being deleted from jclouds-labs in the next 1.8.x and 1.9.x releases.
SubnetTier: update PortForwardManager usage
Merge pull request #7 from aledsage/fix/setPortForwardingManager

update PortForwardingManager usage