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: Ia8250db660216a5296cb6ba2af1538b8c90d187c
Closes-Bug: 1301552
Remove sshd reconfig from lib/ironic

The sshd reconfiguration to listen on port 2222 provides no
benefit and complicates deployment on some systems.  This removes
the reconfiguration and instead just confirms SSH connectivity.
Default SSH host and ports are left configurable, but the port now
reflects the default 22.

Change-Id: Iaf7c71854c3741a505a79037ffb8c86ace74fc27
Merge "Remove sshd reconfig from lib/ironic"
Merge "Devstack support for Neutron VPNaaS"