Merge branch '1082-add-boot-commands-to-vmx-and-ovf-builders' of github.com:rasa/packer into rasa-1082-add-boot-commands-to-vmx-and-ovf-builders

Conflicts:
	builder/virtualbox/ovf/config.go
	builder/vmware/vmx/config.go

vmware-iso/esxi: fix multiple issues with VNC address discovery

builder/googlecompute: uses new auth style

parallels-pvm: Optionally assign new MAC addresses to imported VMs

New config option:
reassign_mac (boolean) - If this is "false" the MAC address of the first
NIC will reused when imported else a new MAC address will be generated by
Parallels. Defaults to "false".

doc openstack builder: region req'd only for rackspace

Modify openstack builder doc to say that specifying a region is only
required for public rackspace and is NOT required for a private
openstack cloud.

Update openstack builder doc to include private openstack example

This illustates how to use the OpenStack builder with a private
OpenStack cloud, as opposed to a public cloud such as Rackspace public
cloud.