Enhance IpRouteCommand class to support IPv6 routes.

[Sridhar Gaddam]

Current implementation of IpRouteCommand class in neutron/agent/linux/ip_lib.py needs enhancement to support IPv6 routes.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/154451

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/157555

[OpenStack Infra (hudson-openstack)]

Change abandoned by Sridhar Gaddam (<email address hidden>) on branch: master
Review: https://review.openstack.org/154451
Reason: Abandoning in favor of the following patch - https://review.openstack.org/#/c/157555/3

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/157555
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=b9e02f22ef20c2080e95b582694063165e920b66
Submitter: Jenkins
Branch: master

commit b9e02f22ef20c2080e95b582694063165e920b66
Author: Brian Haley <email address hidden>
Date: Thu Feb 19 14:50:43 2015 -0500

    Change linux/ip_lib code to better handle address families

    The code in linux/ip_lib doesn't handle IP address families
    similarly amongst all its APIs. It also doesn't consistently
    handle how it passes options and arguments along to /sbin/ip

    So in the spirit of re-factoring, let's try and fix that:

    1. Have the code determine the IP address family from its
       arguments, given that it was passed an IP address.

    2. Always follow an (options, command, arguments) style.
       Options need a '-' prepended and go first, followed by the
       command, and finally by any arguments.

    3. In cases where we can't infer an address family but need
       one it is now required (e.g. listing routes).

    I also cleaned-up the IpRule class to fall in line with the
    other classes.

    Change-Id: Idcb9af698e3ea2d99a6a281c86fa13f51499b628
    Closes-Bug: #1419805