Don't manage the nova uid/gid if nova_{user,group}_id is undef

Any user modification before standard system package creates the
user is wrong. Usecase of patch adding the user is also broken as
there are several other options: provide user before whole class
nova, have user id enforced by package or as most humans do accept
that in multi host enviroments there are 3 layers - user, group and
netgroup. In all cases nova puppet module should never touch the
user as it's provided by package on all supported systems, but for
backwards compatibility the management of user is disabled if
nova_group_id is undef or if nova_user_id is undef.

Closes-Bug: rhbz#1115946
Change-Id: If22b27f5fb78ba6821f4d6e8c275f8b80c70dd59
Merge "Don't manage the nova uid/gid if nova_{user,group}_id is undef"
Control the number of workers for nova-conductor service

Closes-bug: #1286891

Change-Id: If2dd01b2267706b57e8b6b386b08bc9d9654cd90
Deprecate conductor_workers in nova::api

Since we now have a dedicated nova::conductor class, the
conductor_workers parameter in nova::api isn't at his right place.
This commit deprecate the conductor_workers parameter in profit of
workers param in nova::conductor ( see https://review.openstack.org/106656/ )

Change-Id: I767b5c143f12a0f518828287b33aedbfd2201e72
Merge "Deprecate conductor_workers in nova::api"