Generate a .xe shell script which can upload to a xapi host/ XenServer

The script needs:
* the xe binary
* the xe-unikernel-upload binary
* a $HOME/.xe config file

Signed-off-by: David Scott <dave.scott@citrix.com>
chmod name.xe to 0o755

Signed-off-by: David Scott <dave.scott@citrix.com>
Bug fixes in generated .xe shell script

Signed-off-by: David Scott <dave.scott@citrix.com>