Adding initial README
Adding initial README

Signed-off-by: Rob Dobson <564e7c9301873eb0e5b6866dcaa1b131933d2ed5@citrix.com>

june07/packer-builder-xenserver,june07/packer-builder-xenserver,dongyuzheng/packer-builder-xenserver,fr34k8/packer-builder-xenserver,dongyuzheng/packer-builder-xenserver,rdobson/packer-builder-xenserver,xenserverarmy/packer,makunterry/packer-builder-xenserver,simonfuhrer/packer-builder-xenserver-1,xenserverarmy/packer,makunterry/packer-builder-xenserver,fr34k8/packer-builder-xenserver,simonfuhrer/packer-builder-xenserver-1,rdobson/packer-builder-xenserver,conceptboard/packer,conceptboard/packer