ofagent: Add a missing push_vlan action

Fix the flow for _provision_local_vlan_inbound_for_tunnel
to push-vlan explicitly.  While the old code happened to
work with older versions of OVS, it was spec-wise incorrect because
it failed to meet the prerequisite of the following set-field.
The latest version of OVS correctly rejects such a flow.

Closes-Bug: #1308927
Change-Id: I66221eec0cb4083d178d7d5651360ee1874e3d1b
Add 'secret' property for 'connection' option

Neutron cli registers 'connection' option without
'secret=True' property. This commit makes sure
'connection' option has 'secret' property when
it is registered.

Change-Id: I0b0a5aca44a8eeee1c12513f30b9559f1d008442
Closes-Bug: #1319651
Merge "Add 'secret' property for 'connection' option"
Merge "ofagent: Add a missing push_vlan action"