Remove deprecated instance_type alias from nova-manage

Was deprecated in Havana, so now that we are in Icehouse lets
remove it.

UpgradeImpact
Change-Id: Ieb3775e0a43084d00624f9e1d8b879c312e32b3c
Deprecate/remove scheduler select_hosts()

This call is no longer used and can be removed from the scheduler api and
drivers. For backwards compatibility, the existing manager method is kept
but instead call driver.select_destinations() and convert the result to
the old format.

Conductor manager, as the last user of this call, used it to select
a target for live migration, but now instead makes calls to
select_destinations() to get the same information. The related change
to conductor manager is here: https://review.openstack.org/#/c/52311/

Change-Id: I702515a086e7f33c48fa9ee106271c868b660540
Spelling fix resouce=>resource

Change-Id: I369d925573e6ce7b48f610051f3b53a4afbb3d0d
Avoid unnecessary use of rootwrap for some network commands

Every time we run something as root with rootwrap, it takes about
ten times longer (setup-wise anyway). For things that don't need
to be run as root, we should avoid this hit. Nova network does
this a lot and is also slow enough to cause trouble, so this
patch attempts to address that for a few situations.

Related-bug: #1257626

Change-Id: Idc26776bf96ccfd9f50383e9d40aa47397d4e2cf
Merge "Deprecate/remove scheduler select_hosts()"
Merge "Spelling fix resouce=>resource"
Merge "Remove deprecated instance_type alias from nova-manage"
Merge "Avoid unnecessary use of rootwrap for some network commands"