xenapi: virt unrescue method now supports objects

Commit 65ad230af5ece020822fa963dd30fd641a54ae91 ensured
that the compute API and manager are now getting objects
for the unrescue method.

This patch adds support to the virt driver code.

Change-Id: Ie6b587d3f89202a6987291bfaea88290241651f2
vmware: VM diagnostics (v3 API only)

There is no formal definition for the VM diagnostics. For the
V2 API the diagnostics will be returned as they are today.

This will support backward compatibility with the existing API's.

Part of the blueprint v3-diagnostics

DocImpact

Change-Id: I6465ee6fc2edac0107e260297d9647c8a16b09ae
VMware: use datastore classes get_allowed_datastores/_sub_folder

Convert the above-mentioned functions to use the datastore utility
classes.

partial blueprint vmware-spawn-refactor
Change-Id: I20c37367c8dca1c8dc20a308ce2cea5229097701
VMware: use datastore classes in file_move/delete/exists, mkdir

Straightforward conversion of a few functions in ds_util to
accepts DatastorePath objects instead of literal strings.

partial blueprint vmware-spawn-refactor
Change-Id: I9dff390ce020dcc39a05184a7ee69902e3412c9f
Revert "Add missing image to instance booted from volume"

This reverts commit c3191cf0ba5ad3dc2df8da2a2bf5c9d270fde9d9.

The change needs to be thought out some more, i.e. why isn't
compute_api.get_all just loading up the image_ref value on the instance
object rather than calling a helper method from the servers extension to
the instance object which just calls back to compute_api, seems very
roundabout, plus isn't it a v3 API issue also?

Conflicts:
	nova/api/openstack/compute/servers.py

Due to: 826aed0 Use oslo.i18n

Change-Id: I6abbfdfa786c3d98065c969e7f9d7d5830caf7e8
Closes-Bug: #1343689
Merge "xenapi: virt unrescue method now supports objects"
Merge "vmware: VM diagnostics (v3 API only)"
Merge "VMware: use datastore classes get_allowed_datastores/_sub_folder"
Merge "Revert "Add missing image to instance booted from volume""
Merge "VMware: use datastore classes in file_move/delete/exists, mkdir"