Ensure keystone endpoint set before service starts

As neutron-server is mostly useless without having the keystone
service+endpoint set, in the case where both keystone and
neutron-server are on the same machine, this patch adds a soft
dependency to ensure that the keystone catalog includes neutron

This has a knock on effect of fixing openstack::provisioner, which
would sometimes try to create neutron networks, the type for which
soft depends on neutron-server, without there being an endpoint
set in the keystone catalog

Change-Id: I658e1b3e2c448b9a7da9e013c4e105b9ec824893
Adds Database Configuration Support for Havana

Previously, database configuration information was stored in the
plugin .ini file.  As of Havana, a [database] section has been
created in neutron.conf to manage the database configuation for
all Neutron plugins:

https://github.com/openstack/neutron/blob/stable/havana/etc/neutron.conf#L315

Additionaly, several database flags have changed from Grizzly to
Havana.  For backwards compatibility, the previously supported
database flags are contained in neutron::server with a default
of false.

Change-Id: I300fc12092bca1abdd105e0c0c272f7fd49258ac