Ensure we don't access the net when building docs

(Note, this has not been sent upstream)

Change-Id: I9d02fb4053a8106672aded1614a2850e21603eb2
remove runtime dep on python-pbr

Change-Id: I6f247f64c561d49c13e3c2f67401fe150b6d47b6
Revert "Replace oslo.sphinx with oslosphinx"

This reverts commit c926216a9bd64d5cdd9731bd34e03613940d32e9.

Conflicts:
	test-requirements.txt
Ignore the image name when booting from volume

In 0185d2445 the _run_instance method was changed to acquire the image
metadata from the request_spec instead of glance. This was needed to be
able to get the image_metadata attached to a volume, when booting from
it. That change didn't consider that the image name key is not inherited
when creating a volume from an image and introduced a bug when creating
the usage_info for volume booted instances.

This change fixes this by only attaching the image name to the usage_info
only when booting from an image and not when booting from a volume.

Related-Bug: 1281973
Change-Id: I8ec441e7815855a94a28c4566790d5144deff16f
(cherry picked from commit 43aaf80942a0afb7471e803e57a3db851dab608b)