added in load balancer and subnet exercise
Refactored code to use chef templates rather than sed to setup ROLE and SEEDADDRESS
Added in semaphores to control access to VBoxManage (a sequential resource)
Updated cluster recipe to setup /etc/hosts
Minor updates to virtualbox driver
Merge branch 'experiment-3' into experiment-4

Conflicts:
	deltacloud/server/lib/deltacloud/drivers/virtualbox/virtualbox_driver.rb