[XEND] Add missing Xen API methods

[XEND] Add missing Xen API methods

* Added session.get_all, task.get_by_name_label,
  host.get_by_name_label, VM.add_to_otherConfig,
  VM.remove_from_otherConfig

* Added implementations for VM.get_VCPUs_policy,
  VM.get_platform_std_vga, VM.get_vm_by_uuid,
  VM.get_platform_localtime, VM.get_platform_clock_offset,
  VM.get_platform_enable_audio, VM.get_platform_keymap,
  VM.get_otherConfig, VM.set_actions_after_shutdown,
  VM.set_actions_after_reboot, VM.set_actions_after_suspend,
  VM.set_actions_after_crash, VM.set_platform_std_VGA,
  VM.set_platform_serial, VM.set_platform_keymap,
  VM.set_platform_localtime, VM.set_platform_clock_offset,
  VM.set_platform_enable_audio, VM.set_otherConfig, VBD.destroy,
  VBD.get_io_read_kbs, VBD.get_io_write_kbs, VBD.get_all, VIF.destroy,
  VIF.get_VM, VIF.get_name, VIF.get_MTU, VIF.get_MAC, VIF.get_type,
  VIF.get_device, VIF.get_io_read_kbs, VIF.get_io_write_kbs,
  VIF.get_all, VTPM.destroy, VTPM.get_all

* Save devid of a device on creation in XendDomainInfo

Signed-off-by: Alastair Tse <atse@xensource.com>