screenshot: Defining the internal API

screenshot: Defining the internal API

* src/driver.h: Stub code for new API
* src/esx/esx_driver.c, src/libxl/libxl_driver.c,
  src/lxc/lxc_driver.c, src/openvz/openvz_driver.c,
  src/phyp/phyp_driver.c, src/qemu/qemu_driver.c,
  rc/remote/remote_driver.c, rc/test/test_driver.c,
  src/uml/uml_driver.c, src/vbox/vbox_tmpl.c,
  src/vmware/vmware_driver.c, src/xen/xen_driver.c,
  src/xen/xen_driver.h, src/xen/xen_hypervisor.c,
  src/xen/xen_inotify.c, src/xen/xend_internal.c,
  src/xen/xm_internal.c, src/xen/xs_internal.c,
  src/xenapi/xenapi_driver.c: Add dummy entries in driver
  table for new APIs