VM.create optional parameter cast issue

For specific reason, we need to use the VM.create call manually (eg when importing a VM from another hypervisor).

When we do so, we are sending mandatory params. But for some optional params, if not sent, are created automatically by XAPI, and failed because of casting issue: INTERNAL_ERROR(Failure("int_of_string"))

We need to pass those extra parameters to make it work:

• shutdown_delay
• start_delay
• version