Enable neutron server to be run in SSL mode

This commit allows one to specify ca, cert and key file
to run neutron server in SSL mode.

Change-Id: I90f36e7c465924105e6b8032909988286f3e5374
Add parameter to set veth MTU

In many applications (including in particular NFV), it is useful
to use jumbo frames on veth pairs.  The OVS agent has a setting
enabling the user to set the MTU on veth interfaces, but it is
currently not exposed as a parameter.  This patch exposes the
veth_mtu setting and adds rspec tests accordingly.

Change-Id: I7b211be29a5630874b1c56e79ca80667f96ce425
Merge "Add parameter to set veth MTU"