Default RABBIT_HOST to be the SERVICE_HOST.

Using localhost for RABBIT_HOST can cause problems - particularly
on systems where IPv6 is partially broken and localhost resolves
to an IPv6 address.

The service should logically be running on SERVICE_HOST unless
otherwise overridden.

Change-Id: I6efb71b8b95174770066f38403d5d428ec88c3b6
Devstack support for Neutron VPNaaS

Includes two enhancements to support VPNaaS and allow other
vendor implementation support. Goal is to provide a solution
for VPN .ini files until a more general solution can be defined
to handle all reference and vendor .ini files.

First, the /opt/stack/neutron/etc/vpn_agent.ini file is copied
to /etc/neutron, to allow the selected device drivers for agent
to be specified. Both reference and vendor implementations can
be uncommented in this file, prior to stacking.

Second, to allow vendor VPN implementations to provide an .ini
file to the agent at start-up time, an environment variable is
defined and can be set in the localrc to specify one or more
.ini files. The desire is NOT to include vendor settings in the
global vpn_agent.ini.

Change-Id: I5370ee57bbe326eff505a53055da4fddc0838de4
Closes-Bug: 1301552
Enabled non-root users to read nfs_shares.conf.

If you use the cinder NFS driver, it will create a file called
nfs_shares.conf, containing a list of NFS shares cinder can
use.  The file is created with 660 permissions and owned by
root:root.  When c-vol starts, it has problems reading
nfs_shares.conf, resulting in a "[Errno 13] Permission denied:
'/etc/cinder/nfs_shares.conf'".  This patch creates
nfs_shares.conf without using sudo, so c-vol can at least
read it.

Change-Id: Ifce2bd4b9ff2191445a1964c1ce09c823d096d68
Closes-Bug: #1297916
Inject the domain name for devstack in tempest

A new setting for the keystone domain name is introduced in
tempest by change https://review.openstack.org/#/c/81872/.

The default value in tempest is set to None, so that it is
not devstack specific. It's up to devstack to configure
the name of the keystone domain defined in devstack.

Partially implements bp multi-keystone-api-version-tests

Change-Id: I3d1406407759e1fdce0704fa2d6aa025f23a5f08
Merge "Default RABBIT_HOST to be the SERVICE_HOST."
Merge "Inject the domain name for devstack in tempest"
Merge "Devstack support for Neutron VPNaaS"
Merge "Enabled non-root users to read nfs_shares.conf."
Merge branch 'master' of https://github.com/openstack-dev/devstack