L3 and DHCP agents need an option to delete namespaces

[Carl Baldwin]

This relates to https://bugs.launchpad.net/neutron/+bug/1052535. The problem with deleting namespaces was found to be caused by the iproute package. See that bug for details.

For those deployments on newer distros with the iproute fix, it should be possible to enable automatic deletion of namespaces. However, this capability should be configurable and turned off by default in order to not adversely affect deployments with broken iproute package.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/56114

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/56114
Committed: http://github.com/openstack/neutron/commit/7336f3bd27d138b3d11d601f977a1e3df2a44b3e
Submitter: Jenkins
Branch: master

commit 7336f3bd27d138b3d11d601f977a1e3df2a44b3e
Author: Carl Baldwin <email address hidden>
Date: Tue Nov 12 19:31:45 2013 +0000

    Optionally delete namespaces when they are no longer needed

    Adds a configuration option to tell the network agents to delete
    namespaces when they are no longer in use. The option defaults to
    False so that the agent will not attempt to delete namespaces in
    environments where this is not safe.

    This has been working well in deployments where iproute2 has been
    patched with commit 58a3e8270fe72f8ed92687d3a3132c2a708582dd or it is
    new enough to include it without being patched.

    Change-Id: Ice5242c6f0446d16aaaa7ee353d674310297ef72
    Closes-Bug: #1250596
    Related-Bug: #1052535

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/havana
Review: https://review.openstack.org/84419

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/84419
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=91657c1612b4cc037c74b77f4b3548f843c10fcd
Submitter: Jenkins
Branch: stable/havana

commit 91657c1612b4cc037c74b77f4b3548f843c10fcd
Author: Carl Baldwin <email address hidden>
Date: Tue Nov 12 19:31:45 2013 +0000

    Optionally delete namespaces when they are no longer needed

    Adds a configuration option to tell the network agents to delete
    namespaces when they are no longer in use. The option defaults to
    False so that the agent will not attempt to delete namespaces in
    environments where this is not safe.

    This has been working well in deployments where iproute2 has been
    patched with commit 58a3e8270fe72f8ed92687d3a3132c2a708582dd or it is
    new enough to include it without being patched.

    Change-Id: Ice5242c6f0446d16aaaa7ee353d674310297ef72
    Closes-Bug: #1250596
    Related-Bug: #1052535
    (cherry picked from commit 7336f3bd27d138b3d11d601f977a1e3df2a44b3e)
    Related-Bug: #1175695