VMware: fix broken mock of ds_util.mkdir

Change I788e33dbcb3dedc41831b976137607274b1c02ca introduced an
incorrect use of mock which had side-effects for other tests. This
change fixes it.

Change-Id: I71188ec7c12d51c2b4a253f13a5f51cc8bc0ae36
VMware: Improve logging of DatastorePath in error messages

Change-Id: I8ad6dc52c460d11f71c750e8cc287b36d8238106
VMware: trivial formatting fix in fake driver

Change-Id: Ie6029896edb51c613bd53b5441df4825588b2334
VMware: Make DatastorePath hashable

Make DatastorePath work properly when used as a key value in a dict or
set.

This change specifically enables a subsequent change in the fake
driver, which stores DatastorePath objects in a set. However, it's
probably a good idea in general as I spent quite some time trying to
work out why it didn't work when I hit it.

Change-Id: Ia5519b84bc47ea1e0a5a70f9368806f762d12db5
Merge "VMware: fix broken mock of ds_util.mkdir"
Merge "VMware: Improve logging of DatastorePath in error messages"
Merge "VMware: trivial formatting fix in fake driver"
Merge "VMware: Make DatastorePath hashable"