Implement local ARP responder onto OVS agent

[OpenStack Infra]

https://review.openstack.org/49227
commit befa0b9184eb0c6248d06efa5b02be8217f1722e
Author: Édouard Thuleau <email address hidden>
Date: Mon Jan 6 13:58:39 2014 +0100

    Implement local ARP responder onto OVS agent

    With ML2 plugin and l2-pop mechanism driver, it's possible to locally
    answer to the ARP request of the VM and avoid ARP broadcasting emulation
    on overlay which is costly.

    When this functionality is enabled, the OVS flows logic evolves to [1].
    This functionality was introduce in 2.1 OVS branch [2].

    A README is added to describe l2-pop mechanism driver and the agents
    particularities.

    [1] https://wiki.openstack.org/wiki/Ovs-flow-logic#OVS_flows_logic_with_local_ARP_responder
    [2] http://git.openvswitch.org/cgi-bin/gitweb.cgi?p=openvswitch;a=commitdiff;h=f6c8a6b163af343c66aea54953553d84863835f7

    DocImpact: New OVS agent flag 'arp_responder' set to false by default
    Closes-Bug: #1237427
    Change-Id: Ic28610faf2df6566d8d876fcd7aed333647970e2

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/105906

[OpenStack Infra (hudson-openstack)]

Change abandoned by Ryan Moats (<email address hidden>) on branch: master
Review: https://review.openstack.org/105906
Reason: As this change appears to need to be made from within the plugin's help text, there is no reason to continue with this
change.

[Andreas Jaeger (jaegerandi)]

The option is documented in the Config Reference now.